Rewrite for-in loop as indexing loop for JavaScript indexable arrays

pkg/compiler/lib/src/ssa/codegen.dart

Index: pkg/compiler/lib/src/ssa/codegen.dart
diff --git a/pkg/compiler/lib/src/ssa/codegen.dart b/pkg/compiler/lib/src/ssa/codegen.dart
index ea200c3cb337ce2af6834488c480f7351e302bed..6e5b80e6d313aff703df3de9aa2cb0a3be67c1b2 100644
--- a/pkg/compiler/lib/src/ssa/codegen.dart
+++ b/pkg/compiler/lib/src/ssa/codegen.dart
@@ -1624,16 +1624,28 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
     Element element = node.element;
     List<DartType> instantiatedTypes = node.instantiatedTypes;
 
-    registry.registerStaticInvocation(element);
-
     if (instantiatedTypes != null && !instantiatedTypes.isEmpty) {
       instantiatedTypes.forEach((type) {
         registry.registerInstantiatedType(type);
       });
     }
 
-    push(backend.emitter.staticFunctionAccess(node.element));
-    push(new js.Call(pop(), visitArguments(node.inputs, start: 0)), node);
+    List<js.Expression> arguments = visitArguments(node.inputs, start: 0);
+
+    if (element == backend.getCheckConcurrentModificationError() &&

[floitsch, 2015/04/17 12:40:34]

Add comments:
We inline the checkConcurrentModificationError function. (We couldn't do it
earlier, since it adds basic blocks that hurt other optimizations).

[sra1, 2015/04/17 18:16:56]

Done.

+        arguments.length == 2) {

[floitsch, 2015/04/17 12:40:33]

Is that check necessary? or should it be an assert?

[sra1, 2015/04/17 18:16:56]

Done.

+      Element throwFunction = backend.getThrowConcurrentModificationError();
+      registry.registerStaticInvocation(throwFunction);
+      push(js.js('# || (0, #)(#)',[

[floitsch, 2015/04/17 12:40:33]

add comment for the "(0, #)".

[sra1, 2015/04/17 18:16:56]

Done.

+          arguments[0],
+          backend.emitter.staticFunctionAccess(throwFunction),
+          arguments[1]]));
+    } else {
+      registry.registerStaticInvocation(element);
+      push(backend.emitter.staticFunctionAccess(element));
+      push(new js.Call(pop(), arguments), node);
+    }
+
   }
 
   visitInvokeSuper(HInvokeSuper node) {