Miscellaneous runtime fixes.

tool/input_sdk/private/ddc_runtime/classes.dart

Index: tool/input_sdk/private/ddc_runtime/classes.dart
diff --git a/tool/input_sdk/private/ddc_runtime/classes.dart b/tool/input_sdk/private/ddc_runtime/classes.dart
index fdc72a361eeef9dcbcd597e2f592c9da9cc6aeb9..d18f86fbe0df3c2ebbd2a2425e94814a1aea8241 100644
--- a/tool/input_sdk/private/ddc_runtime/classes.dart
+++ b/tool/input_sdk/private/ddc_runtime/classes.dart
@@ -281,22 +281,24 @@ defineExtensionNames(names) =>
 
 // Install properties in prototype order.  Properties / descriptors from
 // more specific types should overwrite ones from less specific types.
-_installProperties(jsProto, extProto) {
-  var coreObjProto = JS('', '#.prototype', Object);
-  if (JS('bool', '# === #', extProto, coreObjProto)) {
+_installProperties(jsProto, extProto) => JS('', '''(() => {
+  let coreObjProto = $Object.prototype;
+  if (extProto === coreObjProto) {
     // core.Object members need to be copied from the non-symbol name to the
     // symbol name.
-    for (var name in getOwnPropertyNames(coreObjProto)) {
-      var desc = getOwnPropertyDescriptor(coreObjProto, name);
-      defineProperty(jsProto, getExtensionSymbol(name), desc);
+    let names = $getOwnPropertyNames(coreObjProto);
+    for (var i = 0; i < names.length; ++i) {

[Jennifer Messerly, 2016/05/11 19:56:26]

nit: use `let` if writing JS code

[Leaf, 2016/05/12 17:00:44]

Done.

+      let name = names[i];

[Jennifer Messerly, 2016/05/11 19:56:26]

fyi ... there is a way to write this in Dart without converting it back to the
old pattern (that I've been slowly trying to remove).

This would work:

var names = getOwnPropertyNames(coreObjProto);
for (int i = 0; i < JS('int', '#.length', names); ++i) {
    var name = JS('', '#[#], names, i);
    ...
}


That said, if we're microoptimizing, maybe we need to convert large chunks of
the runtime back to a .js file.

[Leaf, 2016/05/12 17:00:44]

Done.

+      let desc = $getOwnPropertyDescriptor(coreObjProto, name);
+      $defineProperty(jsProto, $getExtensionSymbol(name), desc);
     }
     return;
   }
-  if (JS('bool', '# !== #', jsProto, extProto)) {
-    _installProperties(jsProto, JS('', '#.__proto__', extProto));
+  if (jsProto !== extProto) {
+    $_installProperties(jsProto, extProto.__proto__);
   }
-  copyTheseProperties(jsProto, extProto, getOwnPropertySymbols(extProto));
-}
+  $copyTheseProperties(jsProto, extProto, $getOwnPropertySymbols(extProto));
+})()''');
 
 ///
 /// Copy symbols from the prototype of the source to destination.