chore(build): replace traceur-runtime with es6-shim.

This removes traceur as a dependency for the t push -f
angular2 build.

Closes #4148

modules/angular1_router/lib/facades.es5

@@ -128,7 +128,7 @@ var StringMapWrapper = {
   },
 
   forEach: function (m, fn) {
-    for (prop in m) {
+    for (var prop in m) {
       if (m.hasOwnProperty(prop)) {
         fn(m[prop], prop);
       }