Work around Safari for-in bug.

dart/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js.js_emitter;
 
 
 class OldEmitter implements Emitter {
   final Compiler compiler;
   final CodeEmitterTask task;
@@ skipping 402 matching lines @@
                      classFieldsExtractorAssignment,
                      instanceFromClassIdAssignment,
                      initializeEmptyInstanceAssignment]);
     }
 
     return result;
   }
 
   /** Needs defineClass to be defined. */
   jsAst.Expression buildInheritFrom() {
-    jsAst.Expression result = js(r'''
+    jsAst.Expression result = js(r"""
         function() {
           function tmp() {}
-          var hasOwnProperty = Object.prototype.hasOwnProperty;
           return function (constructor, superConstructor) {
             if (superConstructor == null) {
               // Fix up the the Dart Object class' prototype.
               var prototype = constructor.prototype;
               prototype.constructor = constructor;
               prototype.#isObject = constructor;
               return prototype;
             }
             tmp.prototype = superConstructor.prototype;
             var object = new tmp();
             var properties = constructor.prototype;
-            for (var member in properties) {
-              if (hasOwnProperty.call(properties, member)) {
-                object[member] = properties[member];
-              }
+            var members = Object.keys(properties);
+            var members_length = members.length;

[floitsch, 2015/02/20 14:03:38]

No need to do this. In fact Slava showed that this actually slows down JS VMs.

[ahe, 2015/02/20 14:32:15]

Done.

+            var member;
+            for (var i = 0; i < members_length; ++i) {

[floitsch, 2015/02/20 14:03:38]

I prefer i++.

[ahe, 2015/02/20 14:32:16]

Done.

+              member = members[i];

[floitsch, 2015/02/20 14:03:38]

var member = members[i]  (no need to hoist the "var declaration".

The js-parser will move the "var"s into one line on the top of the function
anyway.

[ahe, 2015/02/20 14:32:15]

I actually put it there to make the hoisting explicit :-)

[ahe, 2015/02/20 14:32:15]

Done.

+              object[member] = properties[member];
             }
             // Use a function for `true` here, as functions are stored in the
             // hidden class and not as properties in the object.
             object[#operatorIsPrefix + constructor.name] = constructor;
             object.constructor = constructor;
             constructor.prototype = object;
             return object;
           };
         }()
-      ''', { 'operatorIsPrefix' : js.string(namer.operatorIsPrefix),
+      """, { 'operatorIsPrefix' : js.string(namer.operatorIsPrefix),
              'isObject' : namer.operatorIs(compiler.objectClass) });
     if (compiler.hasIncrementalSupport) {
       result = js(
           r'#.inheritFrom = #', [namer.accessIncrementalHelper, result]);
     }
     return js(r'var inheritFrom = #', [result]);
   }
 
   jsAst.Statement buildFinishClass(bool hasNativeClasses) {
     String specProperty = '"${namer.nativeSpecProperty}"';  // "%"
@@ skipping 29 matching lines @@
 
         if (#needsMixinSupport) {
           if (superclass && superclass.indexOf("+") > 0) {
             var s = superclass.split("+");
             superclass = s[0];
             var mixinClass = s[1];
             finishClass(mixinClass);
             var mixin = allClasses[mixinClass];
             var mixinPrototype = mixin.prototype;
             var clsPrototype = allClasses[cls].prototype;
-            for (var d in mixinPrototype) {
-              if (hasOwnProperty.call(mixinPrototype, d) &&
-                  !hasOwnProperty.call(clsPrototype, d))
+
+            var properties = Object.keys(mixinPrototype);
+            var properties_length = properties.length;

[floitsch, 2015/02/20 14:03:38]

ditto.

[ahe, 2015/02/20 14:32:15]

Done.

+            var d;

[floitsch, 2015/02/20 14:03:38]

ditto.

[ahe, 2015/02/20 14:32:16]

Done.

+            for (var i = 0; i < properties_length; ++i) {
+              d = properties[i];
+              if (!hasOwnProperty.call(clsPrototype, d))
                 clsPrototype[d] = mixinPrototype[d];
             }
           }
         }
 
         // The superclass is only false (empty string) for the Dart Object
         // class.  The minifier together with noSuchMethod can put methods on
         // the Object.prototype object, and they show through here, so we check
         // that we have a string.
         if (!superclass || typeof superclass != "string") {
@@ skipping 493 matching lines @@
 
         // We replace the old Isolate function with a new one that initializes
         // all its fields with the initial (and often final) value of all
         // globals.
         //
         // We also copy over old values like the prototype, and the
         // isolateProperties themselves.
         $finishIsolateConstructorName = function (oldIsolate) {
           var isolateProperties = oldIsolate.#isolatePropertiesName;
           function Isolate() {
-            var hasOwnProperty = Object.prototype.hasOwnProperty;
-            for (var staticName in isolateProperties)
-              if (hasOwnProperty.call(isolateProperties, staticName))
-                this[staticName] = isolateProperties[staticName];
+
+            var staticNames = Object.keys(isolateProperties);
+            var staticNames_length = staticNames.length;

[floitsch, 2015/02/20 14:03:38]

ditto.

[ahe, 2015/02/20 14:32:16]

Done.

+            var staticName;

[floitsch, 2015/02/20 14:03:38]

ditto.

[ahe, 2015/02/20 14:32:16]

Done.

+            for (var i = 0; i < staticNames_length; ++i) {
+              staticName = staticNames[i];
+              this[staticName] = isolateProperties[staticName];
+            }
 
             // Reset lazy initializers to null.
             // When forcing the object to fast mode (below) v8 will consider
             // functions as part the object's map. Since we will change them
             // (after the first call to the getter), we would have a map
             // transition.
             var lazies = init.lazies;
-            for (var lazyInit in lazies) {
-               this[lazies[lazyInit]] = null;
+            var lazyInitializers = Object.keys(lazies);
+            var lazyInitializers_length = lazyInitializers.length;

[floitsch, 2015/02/20 14:03:38]

ditto.

[ahe, 2015/02/20 14:32:15]

Done.

+            for (var i = 0; i < lazyInitializers_length; ++i) {
+               this[lazies[lazyInitializers[i]]] = null;
             }
 
             // Use the newly created object as prototype. In Chrome,
             // this creates a hidden class for the object and makes
             // sure it is fast to access.
             function ForceEfficientMap() {}
             ForceEfficientMap.prototype = this;
             new ForceEfficientMap();
 
             // Now, after being a fast map we can set the lazies again.
-            for (var lazyInit in lazies) {
-              var lazyInitName = lazies[lazyInit];
+            for (var i = 0; i < lazyInitializers_length; ++i) {
+              var lazyInitName = lazies[lazyInitializers[i]];
               this[lazyInitName] = isolateProperties[lazyInitName];
             }
           }
           Isolate.prototype = oldIsolate.prototype;
           Isolate.prototype.constructor = Isolate;
           Isolate.#isolatePropertiesName = isolateProperties;
           if (#outputContainsConstantList) {
             Isolate.#makeConstListProperty = oldIsolate.#makeConstListProperty;
           }
           if (#hasIncrementalSupport) {
@@ skipping 945 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }