fixes #157, renaming local library identifiers if needed.

lib/runtime/dart/_internal.js

-var _internal;
-(function(exports) {
+var _internal = dart.defineLibrary(_internal, {});
+var core = dart.import(core);
+var collection = dart.import(collection);
+var math = dart.lazyImport(math);
+var _interceptors = dart.lazyImport(_interceptors);
+var _js_primitives = dart.lazyImport(_js_primitives);
+(function(exports, core, collection, math, _interceptors, _js_primitives) {
   'use strict';
   class EfficientLength extends core.Object {}
   let ListIterable$ = dart.generic(function(E) {
     class ListIterable extends collection.IterableBase$(E) {
       ListIterable() {
         super.IterableBase();
       }
       get [core.$iterator]() {
         return new (ListIterator$(E))(this);
       }
@@ skipping 2020 matching lines @@
   exports.ReversedListIterable$ = ReversedListIterable$;
   exports.ReversedListIterable = ReversedListIterable;
   exports.UnmodifiableListError = UnmodifiableListError;
   exports.NonGrowableListError = NonGrowableListError;
   exports.makeListFixedLength = makeListFixedLength;
   exports.Lists = Lists;
   exports.printToConsole = printToConsole;
   exports.Sort = Sort;
   exports.Symbol = Symbol;
   exports.POWERS_OF_TEN = POWERS_OF_TEN;
-})(_internal || (_internal = {}));
+})(_internal, core, collection, math, _interceptors, _js_primitives);