Fix js_test in dart2js checked mode

sdk/lib/js/dart2js/js_dart2js.dart

Index: sdk/lib/js/dart2js/js_dart2js.dart
diff --git a/sdk/lib/js/dart2js/js_dart2js.dart b/sdk/lib/js/dart2js/js_dart2js.dart
index d92d32f02fe1978fa8370ee626823904bf4276c8..8532c197ddd68c3a42d3d7789d9977c43904956c 100644
--- a/sdk/lib/js/dart2js/js_dart2js.dart
+++ b/sdk/lib/js/dart2js/js_dart2js.dart
@@ -376,13 +376,17 @@ class JsArray<E> extends JsObject with ListMixin<E> {
 
   // Methods required by ListMixin
 
-  E operator [](int index) {
-    _checkIndex(index);
+  E operator [](index) {
+    if (index is num && index == index.toInt()) {

[Jacob, 2013/10/29 22:08:03]

can you file a bug to find a better long term solution?

[justinfagnani, 2013/10/30 02:16:36]

Done.

+      _checkIndex(index);
+    }
     return super[index];
   }
 
-  void operator []=(int index, E value) {
-    _checkIndex(index);
+  void operator []=(index, E value) {
+    if (index is num && index == index.toInt()) {
+      _checkIndex(index);
+    }
     super[index] = value;
   }
 
@@ -507,6 +511,8 @@ Object _convertToDart(o) {
   } else if (JS('bool', '# instanceof Date', o)) {
     var ms = JS('num', '#.getMilliseconds()', o);
     return new DateTime.fromMillisecondsSinceEpoch(ms);
+  } else if (JS('bool', '#.constructor === DartObject', o)) {
+    return JS('', '#.o', o);
   } else {
     return _wrapToDart(o);
   }
@@ -519,8 +525,6 @@ JsObject _wrapToDart(o) {
   } else if (JS('bool', '# instanceof Array', o)) {
     return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
         (o) => new JsArray._fromJs(o));
-  } else if (JS('bool', '#.constructor === DartObject', o)) {
-    return JS('', '#.o', o);
   } else {
     return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
         (o) => new JsObject._fromJs(o));