fixes #157, renaming local library identifiers if needed.

lib/runtime/dart/_isolate_helper.js

Index: lib/runtime/dart/_isolate_helper.js
diff --git a/lib/runtime/dart/_isolate_helper.js b/lib/runtime/dart/_isolate_helper.js
index c23f82c2f888c8ac3d893727129469ebc9e45655..fd8d33eb6f3739cccd6ec6963cfd67aec56933df 100644
--- a/lib/runtime/dart/_isolate_helper.js
+++ b/lib/runtime/dart/_isolate_helper.js
@@ -1,5 +1,5 @@
-var _isolate_helper;
-(function(exports) {
+var _isolate_helper, core, _native_typed_data, _interceptors, _js_helper, isolate, _foreign_helper, _js_embedded_names, collection, async;
+(function(exports, core, _native_typed_data, _interceptors, _js_helper, isolate, _foreign_helper, _js_embedded_names, collection, async) {
   'use strict';
   // Function _serializeMessage: (dynamic) → dynamic
   function _serializeMessage(message) {
@@ -1384,4 +1384,4 @@ var _isolate_helper;
   exports.TimerImpl = TimerImpl;
   exports.hasTimer = hasTimer;
   exports.CapabilityImpl = CapabilityImpl;
-})(_isolate_helper || (_isolate_helper = {}));
+})(_isolate_helper || (_isolate_helper = {}), core, _native_typed_data, _interceptors || (_interceptors = {}), _js_helper || (_js_helper = {}), isolate, _foreign_helper, _js_embedded_names, collection, async);