fix list initializers

lib/runtime/dart_runtime.js

 // 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.
 
 var dart, _js_helper;
 (function (dart) {
   'use strict';
 
   let defineProperty = Object.defineProperty;
   let getOwnPropertyDescriptor = Object.getOwnPropertyDescriptor;
@@ skipping 66 matching lines @@
   }
   dart.dcall = dcall;
 
   function dsend(obj, method/*, ...args*/) {
     let args = Array.prototype.slice.call(arguments, 2);
     return checkAndCall(obj[method], obj, args, method);
   }
   dart.dsend = dsend;
 
   function dindex(obj, index) {
+    // TODO(jmesserly): remove this special case once Array extensions are
+    // hooked up.
+    if (obj instanceof Array && getRuntimeType(index) == core.int) {
+      return obj[index];
+    }
     return checkAndCall(obj.get, obj, [index], '[]');
   }
   dart.dindex = dindex;
 
   function dsetindex(obj, index, value) {
     return checkAndCall(obj.set, obj, [index, value], '[]=');
   }
   dart.dsetindex = dsetindex;
 
   function cast(obj, type) {
     // TODO(vsm): handle non-nullable types
     if (obj == null) return obj;
     let actual = getRuntimeType(obj);
     if (isSubtype(actual, type)) return obj;
     throw new _js_helper.CastErrorImplementation(actual, type);
   }
   dart.as = cast;
 
+
+  // TODO(vsm): How should we encode the runtime type?
+  let runtimeType = Symbol('runtimeType');
+
   /**
    * Returns the runtime type of obj. This is the same as `obj.runtimeType`
    * but will not call an overridden getter.
    *
    * Currently this will return null for non-Dart objects.
    */
   function getRuntimeType(obj) {
     switch (typeof obj) {
       case "undefined":
         return core.Null;
       case "number":
         return Math.floor(obj) == obj ? core.int : core.double;
       case "boolean":
         return core.bool;
       case "string":
         return core.String;
       case "symbol":
         return Symbol;
     }
     // Undefined is handled above. For historical reasons,
     // typeof null == "object" in JS.
     if (obj === null) return core.Null;
     // TODO(vsm): Should we treat Dart and JS objects differently here?
     // E.g., we can check if obj instanceof core.Object to differentiate.
-    var result = obj[dart.runtimeType];
+    var result = obj[runtimeType];
     if (result) return result;
     result = obj.constructor;
     if (result == Function) {
       return getFunctionType(obj);
     }
     return result;
   }
   dart.getRuntimeType = getRuntimeType;
 
   function instanceOf(obj, type) {
@@ skipping 619 matching lines @@
           }
           map.set(arg, value);
         }
       }
       return value;
     }
     return makeGenericType;
   }
   dart.generic = generic;
 
+  /** Sets the runtime type of `obj` to be `type` */
+  function setType(obj, type) {
+    obj[runtimeType] = type;
+  }
+  dart.setType = setType;
+
   // TODO(jmesserly): right now this is a sentinel. It should be a type object
   // of some sort, assuming we keep around `dynamic` at runtime.
   dart.dynamic = { toString() { return 'dynamic'; } };
   dart.void = { toString() { return 'void'; } };
   dart.bottom = { toString() { return 'bottom'; } };
 
-  // TODO(vsm): How should we encode the runtime type?
-  dart.runtimeType = Symbol('runtimeType');
-
   dart.JsSymbol = Symbol;
 
   // TODO(jmesserly): hack to bootstrap the SDK
   _js_helper = _js_helper || {};
   _js_helper.checkNum = notNull;
 
 })(dart || (dart = {}));