dart2js: add common names to mangledGlobalNames in new emitter.

tests/language/mixin_type_parameters_simple_test.dart

Index: tests/language/mixin_type_parameters_simple_test.dart
diff --git a/tests/language/mixin_type_parameters_simple_test.dart b/tests/language/mixin_type_parameters_simple_test.dart
index 0df7996d20d6cc8935530e5fd34a213342f5c538..c077cabaeedccafbf82d5dd32a277595b5a74875 100644
--- a/tests/language/mixin_type_parameters_simple_test.dart
+++ b/tests/language/mixin_type_parameters_simple_test.dart
@@ -18,6 +18,9 @@ class A<T> extends S with M1<T> , M2<T> { }
 
 main() {
   var a = new A<int>();
+  // Getting "int" when calling toString() on the int type is not required.
+  // However, we want to keep the original names for the most common core types
+  // so we make sure to handle these specifically in the compiler.
   Expect.equals("int", a.m1().toString());
   Expect.equals("int", a.m2().toString());
   a = new A<String>();