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..90a3ae1273bb2d09ae99aa35f2dfd28752e9230f 100644
--- a/pkg/compiler/lib/src/ssa/codegen.dart
+++ b/pkg/compiler/lib/src/ssa/codegen.dart
@@ -1632,8 +1632,21 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
       });
     }
 
-    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);
+    Element target = node.element;
+    js.Expression test = null;
+    if (target == backend.getThrowConcurrentModificationError() &&
+        arguments.length == 2) {
+      push(js.js('# || (0, #)(#)',[
+          arguments[0],
+          backend.emitter.staticFunctionAccess(node.element),
+          arguments[1]]));
+    } else {
+      push(backend.emitter.staticFunctionAccess(node.element));
+      push(new js.Call(pop(), arguments), node);
+    }
+
   }
 
   visitInvokeSuper(HInvokeSuper node) {