Miscellaneous runtime fixes.

tool/input_sdk/private/ddc_runtime/classes.dart

 // Copyright (c) 2015, 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.
 
 /// This library defines the operations that define and manipulate Dart
 /// classes.  Included in this are:
 ///   - Generics
 ///   - Class metadata
 ///   - Extension methods
 ///
@@ skipping 263 matching lines @@
     JS('', 'dartx[#] = #', name, sym);
   }
   return sym;
 }
 
 defineExtensionNames(names) =>
     JS('', '#.forEach(#)', names, getExtensionSymbol);
 
 // 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.
 /// These are the only properties safe to copy onto an existing public
 /// JavaScript class.
 ///
 registerExtension(jsType, dartExtType) => JS('', '''(() => {
   // TODO(vsm): Not all registered js types are real.
   if (!jsType) return;
 
@@ skipping 76 matching lines @@
 })()''');
 
 /// Sets the element type of a list literal.
 list(obj, elementType) =>
     JS('', '$setType($obj, ${getGenericClass(JSArray)}($elementType))');
 
 setBaseClass(derived, base) => JS('', '''(() => {
   // Link the extension to the type it's extending as a base class.
   $derived.prototype.__proto__ = $base.prototype;
 })()''');