diff --git a/user/super/com/google/gwt/emul/java/lang/NullPointerException.java b/user/super/com/google/gwt/emul/java/lang/NullPointerException.java
index 2425878..3bb6113 100644
--- a/user/super/com/google/gwt/emul/java/lang/NullPointerException.java
+++ b/user/super/com/google/gwt/emul/java/lang/NullPointerException.java
@@ -15,7 +15,6 @@
  */
 package java.lang;
 
-import jsinterop.annotations.JsPackage;
 import jsinterop.annotations.JsType;
 
 /**
@@ -41,7 +40,7 @@
     return new NativeTypeError(msg);
   }
 
-  @JsType(isNative = true, name = "TypeError", namespace = JsPackage.GLOBAL)
+  @JsType(isNative = true, name = "TypeError", namespace = "<window>")
   private static class NativeTypeError {
     NativeTypeError(String msg) { }
   }
diff --git a/user/super/com/google/gwt/emul/java/lang/Throwable.java b/user/super/com/google/gwt/emul/java/lang/Throwable.java
index e636ec3..589e7aa 100644
--- a/user/super/com/google/gwt/emul/java/lang/Throwable.java
+++ b/user/super/com/google/gwt/emul/java/lang/Throwable.java
@@ -25,7 +25,6 @@
 import javaemul.internal.JsUtils;
 import javaemul.internal.annotations.DoNotInline;
 import jsinterop.annotations.JsMethod;
-import jsinterop.annotations.JsPackage;
 import jsinterop.annotations.JsProperty;
 import jsinterop.annotations.JsType;
 
@@ -297,11 +296,11 @@
     return e instanceof NativeTypeError ? new NullPointerException(e) : new JsException(e);
   }
 
-  @JsType(isNative = true, name = "Error", namespace = JsPackage.GLOBAL)
+  @JsType(isNative = true, name = "Error", namespace = "<window>")
   private static class NativeError {
     NativeError(String msg) { }
   }
 
-  @JsType(isNative = true, name = "TypeError", namespace = JsPackage.GLOBAL)
+  @JsType(isNative = true, name = "TypeError", namespace = "<window>")
   private static class NativeTypeError { }
 }
diff --git a/user/test/com/google/gwt/core/client/impl/StackTraceEmulTest.java b/user/test/com/google/gwt/core/client/impl/StackTraceEmulTest.java
index 4553093..6a3822a 100644
--- a/user/test/com/google/gwt/core/client/impl/StackTraceEmulTest.java
+++ b/user/test/com/google/gwt/core/client/impl/StackTraceEmulTest.java
@@ -67,7 +67,7 @@
     String[] methodNames = getTraceJava();
 
     StackTraceElement[] expectedTrace = new StackTraceElement[] {
-        createSTE(methodNames[0], "Throwable.java", 67),
+        createSTE(methodNames[0], "Throwable.java", 66),
         createSTE(methodNames[1], "Exception.java", 29),
         createSTE(methodNames[2], "StackTraceExamples.java", 57),
         createSTE(methodNames[3], "StackTraceExamples.java", 52),
diff --git a/user/test/com/google/gwt/emultest/java/lang/JsExceptionTest.java b/user/test/com/google/gwt/emultest/java/lang/JsExceptionTest.java
index 245ee41..0040c55 100644
--- a/user/test/com/google/gwt/emultest/java/lang/JsExceptionTest.java
+++ b/user/test/com/google/gwt/emultest/java/lang/JsExceptionTest.java
@@ -18,6 +18,10 @@
 
 import com.google.gwt.testing.TestUtils;
 
+import jsinterop.annotations.JsMethod;
+import jsinterop.annotations.JsPackage;
+import jsinterop.annotations.JsType;
+
 /**
  * Unit tests for JsException behavior.
  */
@@ -37,21 +41,21 @@
   }
 
   public void testCatchJava() {
-    Object jso = makeJSO();
-    Exception e = createJsException(jso);
-    assertJsException(jso, catchJava(createThrower(e)));
+    Object obj = new Object();
+    Exception e = createJsException(obj);
+    assertJsException(obj, catchJava(createThrower(e)));
   }
 
   public void testCatchNative() {
-    Object jso = makeJSO();
-    Exception e = createJsException(jso);
-    assertSame(jso, catchNative(createThrower(e)));
+    Object obj = new Object();
+    Exception e = createJsException(obj);
+    assertSame(obj, catchNative(createThrower(e)));
   }
 
   public void testCatchNativePropagatedFromFinally() {
-    Object jso = makeJSO();
-    Exception e = createJsException(jso);
-    assertSame(jso, catchNative(wrapWithFinally(createThrower(e))));
+    Object obj = new Object();
+    Exception e = createJsException(obj);
+    assertSame(obj, catchNative(wrapWithFinally(createThrower(e))));
     assertTrue(keepFinallyAlive);
   }
 
@@ -70,17 +74,14 @@
   }
 
   public void testJavaNativeJavaSandwichCatch() {
-    Object jso = makeJSO();
-    Exception e = createJsException(jso);
-    assertJsException(jso, javaNativeJavaSandwich(e));
+    Object obj = new Object();
+    Exception e = createJsException(obj);
+    assertJsException(obj, javaNativeJavaSandwich(e));
   }
 
   public void testCatchThrowNative() {
     Object e;
 
-    e = makeJSO();
-    assertJsException(e, catchJava(createNativeThrower(e)));
-
     e = "testing";
     assertJsException(e, catchJava(createNativeThrower(e)));
 
@@ -95,9 +96,6 @@
   public void testNativeJavaNativeSandwichCatch() {
     Object e;
 
-    e = makeJSO();
-    assertSame(e, nativeJavaNativeSandwich(e));
-
     e = "testing";
     assertEquals(e, nativeJavaNativeSandwich(e));
     // Devmode will not preserve the same String instance
@@ -125,12 +123,16 @@
     }
   }
 
-  private static native void throwTypeError() /*-{
-    "dummy".notExistsWillThrowTypeError();
-  }-*/;
+  private static void throwTypeError() {
+    Object nullObject = null;
+    nullObject.toString();
+  }
 
-  private static void assertTypeError(RuntimeException e) {
-    assertInstanceOf("TypeError", getBackingJsObject(e));
+  @JsType(isNative = true, namespace = "<window>")
+  private static class TypeError { }
+
+  protected static void assertTypeError(RuntimeException e) {
+    assertTrue(getBackingJsObject(e) instanceof TypeError);
     assertTrue(e.toString().contains("TypeError"));
   }
 
@@ -143,26 +145,24 @@
     }
   }
 
-  private static native void throwSvgError() /*-{
-    // In Firefox, this throws an object (not Error):
-    $doc.createElementNS("http://www.w3.org/2000/svg", "text").getBBox();
+  private static void throwSvgError() {
+    // In old Firefox, this throws an object (not Error):
+    createElementNS("http://www.w3.org/2000/svg", "text").getBBox();
 
     // For other browsers, make sure an exception is thrown to keep the test simple
-    throw new Error("NS_ERROR_FAILURE");
-  }-*/;
+    throw new RuntimeException("NS_ERROR_FAILURE");
+  }
+
+  @JsMethod(name = "document.createElementNS", namespace = JsPackage.GLOBAL)
+  private static native SVGElement createElementNS(String arg1, String arg2);
+
+  @JsType(isNative = true, namespace = JsPackage.GLOBAL)
+  private interface SVGElement {
+    void getBBox();
+  }
 
   private static void assertJsException(Object expected, Throwable exception) {
     assertTrue(exception instanceof RuntimeException);
     assertEquals(expected, getBackingJsObject(exception));
   }
-
-  private static native Object makeJSO() /*-{
-    return {
-      toString : function() {
-        return "jso";
-      },
-      name : "myName",
-      message : "myDescription",
-    };
-  }-*/;
 }
diff --git a/user/test/com/google/gwt/emultest/java/lang/NullPointerExceptionTest.java b/user/test/com/google/gwt/emultest/java/lang/NullPointerExceptionTest.java
index 750f21b..900d97c 100644
--- a/user/test/com/google/gwt/emultest/java/lang/NullPointerExceptionTest.java
+++ b/user/test/com/google/gwt/emultest/java/lang/NullPointerExceptionTest.java
@@ -17,6 +17,8 @@
 
 import com.google.gwt.testing.TestUtils;
 
+import jsinterop.annotations.JsType;
+
 /**
  * Unit tests for the GWT emulation of java.lang.NullPointerException class.
  */
@@ -27,6 +29,9 @@
     return "com.google.gwt.emultest.EmulSuite";
   }
 
+  @JsType(isNative = true, namespace = "<window>")
+  private static class TypeError { }
+
   public void testBackingJsObject() {
     // Do not run the test in JVM.
     if (TestUtils.isJvm()) {
@@ -34,7 +39,7 @@
     }
 
     Object caughtNative = catchNative(createThrower(new NullPointerException("<my msg>")));
-    assertInstanceOf("TypeError", caughtNative);
+    assertTrue(caughtNative instanceof TypeError);
     assertTrue(caughtNative.toString().startsWith("TypeError:"));
     assertTrue(caughtNative.toString().contains("<my msg>"));
     assertTrue(caughtNative.toString().contains(NullPointerException.class.getName()));
diff --git a/user/test/com/google/gwt/emultest/java/lang/ThrowableTest.java b/user/test/com/google/gwt/emultest/java/lang/ThrowableTest.java
index bb08ca7..8e72a6f 100644
--- a/user/test/com/google/gwt/emultest/java/lang/ThrowableTest.java
+++ b/user/test/com/google/gwt/emultest/java/lang/ThrowableTest.java
@@ -17,6 +17,8 @@
 
 import com.google.gwt.testing.TestUtils;
 
+import jsinterop.annotations.JsType;
+
 /**
  * Unit tests for the GWT emulation of java.lang.Throwable class.
  */
@@ -72,7 +74,7 @@
     }
     Throwable e = new Throwable("<my msg>");
     Object caughtNative = catchNative(createThrower(e));
-    assertInstanceOf("Error", caughtNative);
+    assertTrue(caughtNative instanceof Error);
     assertTrue(caughtNative.toString().contains("<my msg>"));
     assertTrue(caughtNative.toString().contains(Throwable.class.getName()));
   }
@@ -89,7 +91,7 @@
     };
 
     Object caughtNative = catchNative(createThrower(e));
-    assertInstanceOf("Error", caughtNative);
+    assertTrue(caughtNative instanceof Error);
     assertTrue(caughtNative.toString().contains("<my msg>"));
     assertTrue(caughtNative.toString().contains(e.getClass().getName()));
   }
@@ -101,4 +103,7 @@
     Throwable e = new Throwable();
     assertSame(e, javaNativeJavaSandwich(e));
   }
+
+  @JsType(isNative = true, namespace = "<window>")
+  private static class Error { }
 }
diff --git a/user/test/com/google/gwt/emultest/java/lang/ThrowableTestBase.java b/user/test/com/google/gwt/emultest/java/lang/ThrowableTestBase.java
index 08f24dc..c5bea6f 100644
--- a/user/test/com/google/gwt/emultest/java/lang/ThrowableTestBase.java
+++ b/user/test/com/google/gwt/emultest/java/lang/ThrowableTestBase.java
@@ -71,8 +71,4 @@
   protected Throwable javaNativeJavaSandwich(Throwable e) {
     return catchJava(createNativeThrower(catchNative(createThrower(e))));
   }
-
-  protected static native void assertInstanceOf(String expectedType, Object e) /*-{
-    return e instanceof window[expectedType];
-  }-*/;
-}
\ No newline at end of file
+}
diff --git a/user/test/org/apache/commons/collections/TestMap.java b/user/test/org/apache/commons/collections/TestMap.java
index 1825d5e..1c4cf29 100644
--- a/user/test/org/apache/commons/collections/TestMap.java
+++ b/user/test/org/apache/commons/collections/TestMap.java
@@ -25,6 +25,9 @@
 import java.util.Map;
 import java.util.Set;
 
+import jsinterop.annotations.JsPackage;
+import jsinterop.annotations.JsProperty;
+
 /**
  * Tests base {@link java.util.Map} methods and contracts.
  * <p>
@@ -370,12 +373,11 @@
       if (TestUtils.isJvm()) {
         return null;
       }
-      return getUndefined0();
+      return getUndefinedImpl();
     }
 
-    private static native Object getUndefined0() /*-{
-      return undefined;
-    }-*/;
+    @JsProperty(name = "undefined", namespace = JsPackage.GLOBAL)
+    private native static Object getUndefinedImpl();
 
     /**
      *  Test to ensure the test setup is working properly.  This method checks