diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/GenerateJavaScriptAST.java b/dev/core/src/com/google/gwt/dev/jjs/impl/GenerateJavaScriptAST.java
index d44f2d0..8d29d1a 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/GenerateJavaScriptAST.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/GenerateJavaScriptAST.java
@@ -527,7 +527,6 @@
     private final JsName arrayLength = objectScope.declareUnobfuscatableName("length");
     private final JsName globalTemp = topScope.declareUnobfuscatableName("_");
     private final JsName prototype = objectScope.declareUnobfuscatableName("prototype");
-    private final JsName call = objectScope.declareUnobfuscatableName("call");
 
     @Override
     public JsExpression transformArrayLength(JArrayLength expression) {
@@ -898,7 +897,7 @@
       JsNameRef methodNameRef;
       if (method.isJsNative()) {
         // Construct Constructor.prototype.jsname or Constructor.
-        methodNameRef = createGlobalQualifier(method.getQualifiedJsName(), sourceInfo);
+        methodNameRef = createGlobalQualifier(method, sourceInfo);
       } else if (method.isConstructor()) {
         /*
          * Constructor calls through {@code this} and {@code super} are always dispatched statically
@@ -980,7 +979,7 @@
       JConstructor ctor = newInstance.getTarget();
       JsName ctorName = names.get(ctor);
       JsNameRef  reference = ctor.isJsNative()
-          ? createGlobalQualifier(ctor.getQualifiedJsName(), sourceInfo)
+          ? createGlobalQualifier(ctor, sourceInfo)
           : ctorName.makeRef(sourceInfo);
       List<JsExpression> arguments = transform(newInstance.getArgs());
 
@@ -1105,7 +1104,7 @@
       JMethod method = jsniMethodRef.getTarget();
       if (method.isJsNative()) {
         // Construct Constructor.prototype.jsname or Constructor.
-        return createGlobalQualifier(method.getQualifiedJsName(), jsniMethodRef.getSourceInfo());
+        return createGlobalQualifier(method, jsniMethodRef.getSourceInfo());
       }
       return names.get(method).makeRef(jsniMethodRef.getSourceInfo());
     }
@@ -1688,7 +1687,7 @@
     }
 
     private JsExpression buildClosureStyleCastMapFromArrayLiteral(
-            List<JsExpression> runtimeTypeIdLiterals, SourceInfo sourceInfo) {
+        List<JsExpression> runtimeTypeIdLiterals, SourceInfo sourceInfo) {
       /*
        * goog.object.createSet('foo', 'bar', 'baz') is optimized by closure compiler into
        * {'foo': !0, 'bar': !0, baz: !0}
@@ -1720,7 +1719,7 @@
     private JsNameRef createStaticReference(JMember member, SourceInfo sourceInfo) {
       assert member.isStatic();
       return member.isJsNative()
-          ? createGlobalQualifier(member.getQualifiedJsName(), sourceInfo)
+          ? createGlobalQualifier(member, sourceInfo)
           : names.get(member).makeRef(sourceInfo);
     }
 
@@ -2015,8 +2014,7 @@
     private void maybeCopyObjProperties(
         JDeclaredType type, JsExpression toPrototype, JsExpression fromPrototype) {
       if (getSuperPrototype(type) != null && !type.isJsFunctionImplementation()) {
-        JsStatement statement =
-        constructInvocation(type.getSourceInfo(),
+        JsStatement statement = constructInvocation(type.getSourceInfo(),
             RuntimeConstants.RUNTIME_COPY_OBJECT_PROPERTIES,
             fromPrototype,
             toPrototype)
@@ -2037,7 +2035,7 @@
     }
 
     private void generateClassDefinition(JDeclaredType type) {
-        assert !program.isRepresentedAsNativeJsPrimitive(type);
+      assert !program.isRepresentedAsNativeJsPrimitive(type);
 
       if (closureCompilerFormatEnabled) {
         generateClosureTypeDefinition(type);
@@ -2242,10 +2240,10 @@
       generatePrototypeAssignment(method, name, rhs, method.getJsMemberType());
     }
 
-     /**
-      * Create a vtable assignment of the form _.polyname = rhs; and register the line as
-      * created for {@code method}.
-      */
+    /**
+     * Create a vtable assignment of the form _.polyname = rhs; and register the line as
+     * created for {@code method}.
+     */
     private void generatePrototypeAssignment(JMethod method, JsName name, JsExpression rhs,
         JsMemberType memberType) {
       SourceInfo sourceInfo = method.getSourceInfo();
@@ -2275,9 +2273,9 @@
 
       JsObjectLiteral definePropertyLiteral =
           JsObjectLiteral.builder(sourceInfo)
-               // {name: {get: function() { ..... }} or {set : function (v) {....}}}
+              // {name: {get: function() { ..... }} or {set : function (v) {....}}}
               .add(name, JsObjectLiteral.builder(sourceInfo)
-                      // {get: function() { ..... }} or {set : function (v) {....}}
+                  // {get: function() { ..... }} or {set : function (v) {....}}
                   .add(method.getJsMemberType().getPropertyAccessorKey(), methodDefinitionStatement)
                   .build())
               .build();
@@ -2335,7 +2333,7 @@
      * variable _ points the JavaScript prototype for {@code type}.
      */
     private void generatePrototypeDefinitions(JDeclaredType type) {
-        assert !program.isRepresentedAsNativeJsPrimitive(type);
+      assert !program.isRepresentedAsNativeJsPrimitive(type);
 
       // Emit synthetic methods first. In JsInterop we allow a more user written method to be named
       // with the same name as a synthetic bridge (required due to generics) relying that the
@@ -2392,24 +2390,6 @@
       }
     }
 
-    public JsNameRef createGlobalQualifier(String qualifier, SourceInfo sourceInfo) {
-      assert !qualifier.isEmpty();
-
-      return JsUtils.createQualifiedNameRef(
-          isQualifiedThroughSpecialGlobalName(qualifier) ? qualifier : ("$wnd." + qualifier),
-          sourceInfo);
-    }
-
-    /*
-     * Some global names are considered special and should be used unqualified. Such names should
-     * not be emitted with the "$wnd." prefix as there seems to be runtime performance implications.
-     * {@see TypeCategory} for the full list.
-     */
-    private boolean isQualifiedThroughSpecialGlobalName(String qualifiedName) {
-      String topLevelName = qualifiedName.split("\\.")[0];
-      return TypeCategory.isSpecialGlobalName(topLevelName);
-    }
-
     /**
      * Returns either _ or ClassCtor.prototype depending on output mode.
      */
@@ -3088,4 +3068,25 @@
   private JsName getIndexedFieldJsName(String indexedName) {
     return names.get(program.getIndexedField(indexedName));
   }
+
+  private static final String WINDOW = "window";
+
+  private static boolean isWindow(String jsNamespace) {
+    return jsNamespace != null
+        && (WINDOW.equals(jsNamespace) || jsNamespace.startsWith(WINDOW + "."));
+  }
+
+  private static JsNameRef createGlobalQualifier(JMember member, SourceInfo sourceInfo) {
+    if (isWindow(member.getJsNamespace())) {
+      return JsUtils.createQualifiedNameRef(
+          member.getQualifiedJsName().substring(WINDOW.length() + 1), sourceInfo);
+    }
+    return createGlobalQualifier(member.getQualifiedJsName(), sourceInfo);
+  }
+
+  private static JsNameRef createGlobalQualifier(String qualifier, SourceInfo sourceInfo) {
+    assert !qualifier.isEmpty();
+
+    return JsUtils.createQualifiedNameRef("$wnd." + qualifier, sourceInfo);
+  }
 }
diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java b/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java
index 0b07d85..a23d114 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/JsInteropRestrictionChecker.java
@@ -1,11 +1,11 @@
 /*
  * Copyright 2015 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
@@ -567,13 +567,10 @@
   private <T extends HasJsName & HasSourceInfo & CanBeJsNative> void checkJsName(T item) {
     if (item.getJsName().isEmpty()) {
       logError(item, "%s cannot have an empty name.", getDescription(item));
-    } else if (JsInteropUtil.isGlobal(item.getJsNamespace()) && item.isJsNative()) {
+    } else if ((item.isJsNative() && !JsUtils.isValidJsQualifiedName(item.getJsName()))
+        || (!item.isJsNative() && !JsUtils.isValidJsIdentifier(item.getJsName()))) {
       // Allow qualified names in the name field for JsPackage.GLOBAL native items for future
       // compatibility
-      if (!JsUtils.isValidJsQualifiedName(item.getJsName())) {
-        logError(item, "%s has invalid name '%s'.", getDescription(item), item.getJsName());
-      }
-    } else if (!JsUtils.isValidJsIdentifier(item.getJsName())) {
       logError(item, "%s has invalid name '%s'.", getDescription(item), item.getJsName());
     }
   }
diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/TypeCategory.java b/dev/core/src/com/google/gwt/dev/jjs/impl/TypeCategory.java
index 6ae81a0..bd4db2c 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/TypeCategory.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/TypeCategory.java
@@ -135,10 +135,6 @@
     return TypeCategory.TYPE_JAVA_OBJECT;
   }
 
-  public static boolean isSpecialGlobalName(String name) {
-    return specialGlobalNames.containsKey(name);
-  }
-
   private static Map<String, TypeCategory> specialGlobalNames =
       ImmutableMap.<String,TypeCategory>builder()
           .put("Object", TYPE_JS_OBJECT)
diff --git a/user/super/com/google/gwt/emul/java/lang/String.java b/user/super/com/google/gwt/emul/java/lang/String.java
index 3722ce2..3beff7c 100644
--- a/user/super/com/google/gwt/emul/java/lang/String.java
+++ b/user/super/com/google/gwt/emul/java/lang/String.java
@@ -157,12 +157,12 @@
   }
 
   @JsType(isNative = true, name = "Function", namespace = JsPackage.GLOBAL)
-  private static class NativeFunction {
-    public native String apply(String thisContext, Object[] argsArray);
+  private static class NativeFunction<T> {
+    public native T apply(Object thisContext, Object[] argsArray);
   }
 
-  @JsProperty(name = "fromCharCode", namespace = "String")
-  private static native NativeFunction getFromCharCodeFunction();
+  @JsProperty(name = "String.fromCharCode", namespace = "window")
+  private static native NativeFunction<String> getFromCharCodeFunction();
 
   public static String valueOf(char[] x) {
     return valueOf(x, 0, x.length);
@@ -410,7 +410,7 @@
   public boolean equals(Object other) {
     // Java equality is translated into triple equality which is a quick to compare strings for
     // equality without any instanceOf checks.
-    return checkNotNull(this) == other;
+    return this == other;
   }
 
   public boolean equalsIgnoreCase(String other) {
@@ -489,11 +489,11 @@
   public int lastIndexOf(String str) {
     return asNativeString().lastIndexOf(str);
   }
-  
+
   public int lastIndexOf(String str, int start) {
     return asNativeString().lastIndexOf(str, start);
   }
-  
+
   @Override
   public int length() {
     return asNativeString().length;
@@ -724,7 +724,7 @@
   public String toUpperCase() {
     return asNativeString().toLocaleUpperCase();
   }
-  
+
   // See the notes in lowerCase pair.
   public String toUpperCase(Locale locale) {
     return locale == Locale.getDefault()
@@ -753,7 +753,7 @@
     return start > 0 || end < length ? substring(start, end) : this;
   }
 
-  @JsType(isNative = true, name = "String", namespace = JsPackage.GLOBAL)
+  @JsType(isNative = true, name = "String", namespace = "window")
   private static class NativeString {
     public static native String fromCharCode(char x);
     public int length;
diff --git a/user/test/com/google/gwt/dev/jjs/optimized/StringOptimizationTest.java b/user/test/com/google/gwt/dev/jjs/optimized/StringOptimizationTest.java
index a42b7a9..e529a00 100644
--- a/user/test/com/google/gwt/dev/jjs/optimized/StringOptimizationTest.java
+++ b/user/test/com/google/gwt/dev/jjs/optimized/StringOptimizationTest.java
@@ -31,7 +31,7 @@
   private static native String getGeneratedFunctionDefintionThatTriggersStringClinit() /*-{
     return function() {
       tmp = @StringOptimizationTest::createString()();
-     }.toString();
+    }.toString();
   }-*/;
 
   public void testStringClinitIsRemoved() throws Exception {
@@ -53,5 +53,4 @@
     String functionDef = getGeneratedFunctionDefintionThatCallsStringFromCharCode();
     assertFunctionMatches(functionDef, "tmp=String.fromCharCode('c')");
   }
-
 }