fixes #157, renaming local library identifiers if needed.

lib/runtime/dart/isolate.js

Index: lib/runtime/dart/isolate.js
diff --git a/lib/runtime/dart/isolate.js b/lib/runtime/dart/isolate.js
index f29e20f81c444a1809c5b6658f512794961e0e58..890f8f0439ffa0a25fdb88f4ea746c6e5f749e84 100644
--- a/lib/runtime/dart/isolate.js
+++ b/lib/runtime/dart/isolate.js
@@ -1,5 +1,8 @@
-var isolate;
-(function(exports) {
+var isolate = dart.defineLibrary(isolate, {});
+var core = dart.lazyImport(core);
+var _isolate_helper = dart.import(_isolate_helper);
+var async = dart.lazyImport(async);
+(function(exports, core, _isolate_helper, async) {
   'use strict';
   class Capability extends core.Object {
     Capability() {
@@ -217,4 +220,4 @@ var isolate;
   exports.ReceivePort = ReceivePort;
   exports.RawReceivePort = RawReceivePort;
   exports.RemoteError = RemoteError;
-})(isolate || (isolate = {}));
+})(isolate, core, _isolate_helper, async);