diff --git a/tools/api-checker/config/gwt20_21userApi.conf b/tools/api-checker/config/gwt20_21userApi.conf
index 6ff8f42..40b1107 100644
--- a/tools/api-checker/config/gwt20_21userApi.conf
+++ b/tools/api-checker/config/gwt20_21userApi.conf
@@ -87,10 +87,12 @@
 
 ##############################################
 #excluded packages
-excludedPackages com.google.gwt.core.client.impl\
+excludedPackages com.google.gwt.benchmarks.client.impl\
+:com.google.gwt.core.client.impl\
 :com.google.gwt.i18n.client.impl\
 :com.google.gwt.i18n.client.impl.cldr\
 :com.google.gwt.i18n.client.impl.plurals\
+:com.google.gwt.junit.client.impl\
 :com.google.gwt.user.client.impl\
 :com.google.gwt.user.client.rpc.impl\
 :com.google.gwt.user.client.ui.impl\
diff --git a/user/src/com/google/gwt/junit/client/impl/ExceptionWrapper.java b/user/src/com/google/gwt/junit/client/impl/ExceptionWrapper.java
index d653ead..8a46f3f 100644
--- a/user/src/com/google/gwt/junit/client/impl/ExceptionWrapper.java
+++ b/user/src/com/google/gwt/junit/client/impl/ExceptionWrapper.java
@@ -18,50 +18,62 @@
 import java.io.Serializable;
 
 /**
- * A helper class for converting a generic {@link Throwable} into an Object that
- * can be serialized for RPC.
+ * Wraps a {@link Throwable}, and explicitly serializes cause and stack trace.
  */
-public final class ExceptionWrapper implements Serializable {
+final class ExceptionWrapper implements Serializable {
 
   /**
-   * Corresponds to {@link Throwable#getCause()}.
+   * Stand-in for the transient {@link Throwable#getCause()} in GWT JRE.
    */
-  public ExceptionWrapper cause;
+  ExceptionWrapper causeWrapper;
 
   /**
-   * Corresponds to {@link Throwable#getMessage()}.
+   * The wrapped exception.
    */
-  public String message;
+  Throwable exception;
 
   /**
-   * Corresponds to {@link Throwable#getStackTrace()}.
+   * Stand-in for the transient {@link Throwable#getStackTrace()} in GWT JRE.
    */
-  public StackTraceWrapper[] stackTrace;
+  StackTraceElement[] stackTrace;
 
   /**
-   * The run-time type of the exception.
+   * If true, the exception's inner stack trace and cause have been initialized.
+   * Defaults to false immediate after deserialization.
    */
-  public String typeName;
-
-  /**
-   * Creates an empty {@link ExceptionWrapper}.
-   */
-  public ExceptionWrapper() {
-  }
+  private transient boolean isExceptionInitialized;
 
   /**
    * Creates an {@link ExceptionWrapper} around an existing {@link Throwable}.
    * 
-   * @param e the {@link Throwable} to wrap.
+   * @param exception the {@link Throwable} to wrap.
    */
-  public ExceptionWrapper(Throwable e) {
-    typeName = e.getClass().getName();
-    message = e.getMessage();
-    stackTrace = StackTraceWrapper.wrapStackTrace(e.getStackTrace());
-    Throwable ecause = e.getCause();
-    if (ecause != null) {
-      cause = new ExceptionWrapper(ecause);
+  public ExceptionWrapper(Throwable exception) {
+    this.exception = exception;
+    this.stackTrace = exception.getStackTrace();
+    Throwable cause = exception.getCause();
+    if (cause != null) {
+      this.causeWrapper = new ExceptionWrapper(cause);
     }
+    this.isExceptionInitialized = true;
   }
 
+  /**
+   * Deserialization constructor.
+   */
+  ExceptionWrapper() {
+    this.isExceptionInitialized = false;
+  }
+
+  public Throwable getException() {
+    if (!isExceptionInitialized) {
+      exception.setStackTrace(stackTrace);
+      if (causeWrapper != null) {
+        exception.initCause(causeWrapper.getException());
+      }
+      isExceptionInitialized = true;
+    }
+    return exception;
+  }
 }
+
diff --git a/user/src/com/google/gwt/junit/client/impl/JUnitResult.java b/user/src/com/google/gwt/junit/client/impl/JUnitResult.java
index 3918349..d5b2449 100644
--- a/user/src/com/google/gwt/junit/client/impl/JUnitResult.java
+++ b/user/src/com/google/gwt/junit/client/impl/JUnitResult.java
@@ -33,9 +33,14 @@
   // Computed at the server, via HTTP header.
   private transient String agent;
 
-  // Deserialized from exceptionWrapper on the server-side
-  private transient Throwable exception;
+  /**
+   * If non-null, check points that were encountered during the run.
+   */
+  private String[] checkPoints;
 
+  /**
+   * If non-null, an exception that occurred during the run.
+   */
   private ExceptionWrapper exceptionWrapper;
 
   // Computed at the server, via HTTP header.
@@ -45,12 +50,12 @@
     return agent;
   }
 
-  public Throwable getException() {
-    return exception;
+  public String[] getCheckPoints() {
+    return checkPoints;
   }
 
-  public ExceptionWrapper getExceptionWrapper() {
-    return exceptionWrapper;
+  public Throwable getException() {
+    return (exceptionWrapper == null) ? null : exceptionWrapper.getException();
   }
 
   public String getHost() {
@@ -61,12 +66,12 @@
     this.agent = agent;
   }
 
-  public void setException(Throwable exception) {
-    this.exception = exception;
+  public void setCheckPoints(String[] checkPoints) {
+    this.checkPoints = checkPoints;
   }
 
-  public void setExceptionWrapper(ExceptionWrapper exceptionWrapper) {
-    this.exceptionWrapper = exceptionWrapper;
+  public void setException(Throwable exception) {
+    this.exceptionWrapper = new ExceptionWrapper(exception);
   }
 
   public void setHost(String host) {
diff --git a/user/src/com/google/gwt/junit/client/impl/StackTraceWrapper.java b/user/src/com/google/gwt/junit/client/impl/StackTraceWrapper.java
deleted file mode 100644
index be2f853..0000000
--- a/user/src/com/google/gwt/junit/client/impl/StackTraceWrapper.java
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
- * Copyright 2006 Google Inc.
- * 
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not
- * use this file except in compliance with the License. You may obtain a copy of
- * the License at
- * 
- * http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations under
- * the License.
- */
-package com.google.gwt.junit.client.impl;
-
-import com.google.gwt.user.client.rpc.IsSerializable;
-
-/**
- * A helper class for converting a generic {@link StackTraceElement} into an
- * Object that can be serialized for RPC.
- */
-public final class StackTraceWrapper implements IsSerializable {
-
-  /**
-   * Creates a {@link StackTraceWrapper} array around an existing
-   * {@link StackTraceElement} array.
-   * 
-   * @param stackTrace the {@link StackTraceElement} array to wrap.
-   */
-  public static StackTraceWrapper[] wrapStackTrace(
-      StackTraceElement[] stackTrace) {
-    int len = stackTrace.length;
-    StackTraceWrapper[] result = new StackTraceWrapper[len];
-    for (int i = 0; i < len; ++i) {
-      result[i] = new StackTraceWrapper(stackTrace[i]);
-    }
-    return result;
-  }
-
-  /**
-   * Corresponds to {@link StackTraceElement#getClassName()}.
-   */
-  public String className;
-
-  /**
-   * Corresponds to {@link StackTraceElement#getFileName()}.
-   */
-  public String fileName;
-
-  /**
-   * Corresponds to {@link StackTraceElement#getLineNumber()}.
-   */
-  public int lineNumber;
-
-  /**
-   * Corresponds to {@link StackTraceElement#getMethodName()}.
-   */
-  public String methodName;
-
-  /**
-   * Creates an empty {@link StackTraceWrapper}.
-   */
-  public StackTraceWrapper() {
-  }
-
-  /**
-   * Creates a {@link StackTraceWrapper} around an existing
-   * {@link StackTraceElement}.
-   * 
-   * @param ste the {@link StackTraceElement} to wrap.
-   */
-  public StackTraceWrapper(StackTraceElement ste) {
-    className = ste.getClassName();
-    fileName = ste.getFileName();
-    lineNumber = ste.getLineNumber();
-    methodName = ste.getMethodName();
-  }
-}
diff --git a/user/src/com/google/gwt/junit/server/JUnitHostImpl.java b/user/src/com/google/gwt/junit/server/JUnitHostImpl.java
index b8e0b87..8db688e 100644
--- a/user/src/com/google/gwt/junit/server/JUnitHostImpl.java
+++ b/user/src/com/google/gwt/junit/server/JUnitHostImpl.java
@@ -22,10 +22,8 @@
 import com.google.gwt.junit.JUnitShell;
 import com.google.gwt.junit.JUnitMessageQueue.ClientInfoExt;
 import com.google.gwt.junit.client.TimeoutException;
-import com.google.gwt.junit.client.impl.ExceptionWrapper;
 import com.google.gwt.junit.client.impl.JUnitHost;
 import com.google.gwt.junit.client.impl.JUnitResult;
-import com.google.gwt.junit.client.impl.StackTraceWrapper;
 import com.google.gwt.user.client.rpc.InvocationException;
 import com.google.gwt.user.server.rpc.HybridServiceServlet;
 import com.google.gwt.user.server.rpc.RPCServletUtils;
@@ -34,8 +32,6 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.Field;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -95,17 +91,6 @@
     return sHost;
   }
 
-  /**
-   * Simple helper method to set inaccessible fields via reflection.
-   */
-  private static <T> void setField(Class<T> cls, String fieldName, T obj,
-      Object value) throws SecurityException, NoSuchFieldException,
-      IllegalArgumentException, IllegalAccessException {
-    Field fld = cls.getDeclaredField(fieldName);
-    fld.setAccessible(true);
-    fld.set(obj, value);
-  }
-
   private Map<StrongName, Map<SymbolName, String>> symbolMaps = new HashMap<StrongName, Map<SymbolName, String>>();
 
   public InitialResponse getTestBlock(int blockIndex, ClientInfo clientInfo)
@@ -128,8 +113,8 @@
       ClientInfo clientInfo) throws TimeoutException {
     for (JUnitResult result : results.values()) {
       initResult(getThreadLocalRequest(), result);
-      ExceptionWrapper ew = result.getExceptionWrapper();
-      result.setException(deserialize(ew));
+      resymbolize(result.getException());
+      addCheckPointElements(result.getException(), result.getCheckPoints());
     }
     JUnitMessageQueue host = getHost();
     ClientInfoExt clientInfoExt = createClientInfo(clientInfo,
@@ -154,6 +139,29 @@
     }
   }
 
+  /**
+   * Creates fake stack trace elements for any checkpoints passed. The elements
+   * are copied in reverse order, so that the last check point is at the top of
+   * the trace.
+   */
+  private void addCheckPointElements(Throwable exception, String[] checkPoints) {
+    if (checkPoints == null) {
+      return;
+    }
+    StackTraceElement[] stackTrace = exception.getStackTrace();
+    StackTraceElement[] newStackTrace = new StackTraceElement[checkPoints.length
+        + stackTrace.length];
+    int pos = checkPoints.length - 1;
+    for (String checkPoint : checkPoints) {
+      newStackTrace[pos] = new StackTraceElement("Check", "point", checkPoint,
+          -1);
+      --pos;
+    }
+    System.arraycopy(stackTrace, 0, newStackTrace, checkPoints.length,
+        stackTrace.length);
+    exception.setStackTrace(newStackTrace);
+  }
+
   private ClientInfoExt createClientInfo(ClientInfo clientInfo,
       HttpServletRequest request) {
     assert (clientInfo.getSessionId() >= 0);
@@ -172,113 +180,6 @@
   }
 
   /**
-   * Deserializes an ExceptionWrapper back into a Throwable.
-   */
-  private Throwable deserialize(ExceptionWrapper ew) {
-    if (ew == null) {
-      return null;
-    }
-
-    Throwable ex = null;
-    Throwable cause = deserialize(ew.cause);
-    try {
-      Class<?> exClass = Class.forName(ew.typeName);
-      try {
-        // try ExType(String, Throwable)
-        Constructor<?> ctor = exClass.getDeclaredConstructor(String.class,
-            Throwable.class);
-        ctor.setAccessible(true);
-        ex = (Throwable) ctor.newInstance(ew.message, cause);
-      } catch (Throwable e) {
-        // try ExType(String)
-        try {
-          Constructor<?> ctor = exClass.getDeclaredConstructor(String.class);
-          ctor.setAccessible(true);
-          ex = (Throwable) ctor.newInstance(ew.message);
-          ex.initCause(cause);
-        } catch (Throwable e2) {
-          // try ExType(Throwable)
-          try {
-            Constructor<?> ctor = exClass.getDeclaredConstructor(Throwable.class);
-            ctor.setAccessible(true);
-            ex = (Throwable) ctor.newInstance(cause);
-            setField(Throwable.class, "detailMessage", ex, ew.message);
-          } catch (Throwable e3) {
-            // try ExType()
-            try {
-              Constructor<?> ctor = exClass.getDeclaredConstructor();
-              ctor.setAccessible(true);
-              ex = (Throwable) ctor.newInstance();
-              ex.initCause(cause);
-              setField(Throwable.class, "detailMessage", ex, ew.message);
-            } catch (Throwable e4) {
-              // we're out of options
-              this.log("Failed to deserialize getException of type '"
-                  + ew.typeName + "'; no available constructor", e4);
-
-              // fall through
-            }
-          }
-        }
-      }
-
-    } catch (Throwable e) {
-      this.log("Failed to deserialize getException of type '" + ew.typeName
-          + "'", e);
-    }
-
-    if (ex == null) {
-      ex = new RuntimeException(ew.typeName + ": " + ew.message, cause);
-    }
-
-    ex.setStackTrace(deserialize(ew.stackTrace));
-    return ex;
-  }
-
-  /**
-   * Deserializes a StackTraceWrapper back into a StackTraceElement.
-   */
-  private StackTraceElement deserialize(StackTraceWrapper stw) {
-    StackTraceElement ste = null;
-
-    Object[] args = resymbolize(stw);
-
-    try {
-      try {
-        // Try the 4-arg ctor (JRE 1.5)
-        Constructor<StackTraceElement> ctor = StackTraceElement.class.getDeclaredConstructor(
-            String.class, String.class, String.class, int.class);
-        ctor.setAccessible(true);
-        ste = ctor.newInstance(args);
-      } catch (NoSuchMethodException e) {
-        // Okay, see if there's a zero-arg ctor we can use instead (JRE 1.4.2)
-        Constructor<StackTraceElement> ctor = StackTraceElement.class.getDeclaredConstructor();
-        ctor.setAccessible(true);
-        ste = ctor.newInstance();
-        setField(StackTraceElement.class, "declaringClass", ste, args[0]);
-        setField(StackTraceElement.class, "methodName", ste, args[1]);
-        setField(StackTraceElement.class, "fileName", ste, args[2]);
-        setField(StackTraceElement.class, "lineNumber", ste, args[3]);
-      }
-    } catch (Throwable e) {
-      this.log("Error creating stack trace", e);
-    }
-    return ste;
-  }
-
-  /**
-   * Deserializes a StackTraceWrapper[] back into a StackTraceElement[].
-   */
-  private StackTraceElement[] deserialize(StackTraceWrapper[] stackTrace) {
-    int len = stackTrace.length;
-    StackTraceElement[] result = new StackTraceElement[len];
-    for (int i = 0; i < len; ++i) {
-      result[i] = deserialize(stackTrace[i]);
-    }
-    return result;
-  }
-
-  /**
    * Returns a client description for the current request.
    */
   private String getClientDesc(HttpServletRequest request) {
@@ -334,30 +235,33 @@
   }
 
   /**
-   * @return {className, methodName, fileName, lineNumber}
+   * Resymbolizes a trace from obfuscated symbols to Java names.
    */
-  private Object[] resymbolize(StackTraceWrapper stw) {
-    Object[] toReturn;
+  private void resymbolize(Throwable exception) {
+    if (exception == null) {
+      return;
+    }
+    StackTraceElement[] stackTrace = exception.getStackTrace();
     StrongName strongName = new StrongName(getPermutationStrongName());
     Map<SymbolName, String> map = loadSymbolMap(strongName);
-    String symbolData = map == null ? null : map.get(new SymbolName(
-        stw.methodName));
-
-    if (symbolData != null) {
-      // jsniIdent, className, memberName, sourceUri, sourceLine
-      String[] parts = symbolData.split(",");
-      assert parts.length == 5 : "Expected 5, have " + parts.length;
-
-      JsniRef ref = JsniRef.parse(parts[0].substring(0,
-          parts[0].lastIndexOf(')') + 1));
-      toReturn = new Object[]{
-          ref.className(), ref.memberName(), stw.fileName, stw.lineNumber};
-
-    } else {
-      // Use the raw data from the client
-      toReturn = new Object[]{
-          stw.className, stw.methodName, stw.fileName, stw.lineNumber};
+    if (map == null) {
+      return;
     }
-    return toReturn;
+    for (int i = 0; i < stackTrace.length; ++i) {
+      StackTraceElement ste = stackTrace[i];
+      String symbolData = map.get(new SymbolName(ste.getMethodName()));
+      if (symbolData != null) {
+        // jsniIdent, className, memberName, sourceUri, sourceLine
+        String[] parts = symbolData.split(",");
+        assert parts.length == 5 : "Expected 5, have " + parts.length;
+
+        JsniRef ref = JsniRef.parse(parts[0].substring(0,
+            parts[0].lastIndexOf(')') + 1));
+        stackTrace[i] = new StackTraceElement(ref.className(),
+            ref.memberName(), ste.getFileName(), ste.getLineNumber());
+      }
+    }
+    exception.setStackTrace(stackTrace);
+    resymbolize(exception.getCause());
   }
 }
diff --git a/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/GWTTestCase.java b/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/GWTTestCase.java
index 0357095..b5755a8 100644
--- a/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/GWTTestCase.java
+++ b/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/GWTTestCase.java
@@ -17,7 +17,6 @@
 
 import com.google.gwt.core.client.GWT;
 import com.google.gwt.core.client.GWT.UncaughtExceptionHandler;
-import com.google.gwt.junit.client.impl.ExceptionWrapper;
 import com.google.gwt.junit.client.impl.GWTRunner;
 import com.google.gwt.junit.client.impl.JUnitResult;
 import com.google.gwt.user.client.Timer;
@@ -305,13 +304,11 @@
 
     JUnitResult myResult = __getOrCreateTestResult();
     if (ex != null) {
-      ExceptionWrapper ew = new ExceptionWrapper(ex);
+      myResult.setException(ex);
       if (checkPoints != null) {
-        for (int i = 0, c = checkPoints.size(); i < c; ++i) {
-          ew.message += "\n" + checkPoints.get(i);
-        }
+        String[] cpArray = checkPoints.toArray(new String[checkPoints.size()]);
+        myResult.setCheckPoints(cpArray);
       }
-      myResult.setExceptionWrapper(ew);
     }
 
     testIsFinished = true;
diff --git a/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/impl/GWTRunner.java b/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/impl/GWTRunner.java
index bf3cb59..4bcca0b 100644
--- a/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/impl/GWTRunner.java
+++ b/user/super/com/google/gwt/junit/translatable/com/google/gwt/junit/client/impl/GWTRunner.java
@@ -245,7 +245,7 @@
     }
     if (result != null && failureMessage != null) {
       RuntimeException ex = new RuntimeException(failureMessage);
-      result.setExceptionWrapper(new ExceptionWrapper(ex));
+      result.setException(ex);
     }   
     TestInfo currentTest = getCurrentTest();
     currentResults.put(currentTest, result);
@@ -357,7 +357,7 @@
       RuntimeException ex = new RuntimeException(currentTest
           + ": could not instantiate the requested class", caught);
       JUnitResult result = new JUnitResult();
-      result.setExceptionWrapper(new ExceptionWrapper(ex));
+      result.setException(ex);
       reportResultsAndGetNextMethod(result);
       return;
     }