fixes #146, JS globals were not understood by the renamer

lib/runtime/dart/collection.js

 var collection;
 (function(exports) {
   'use strict';
   let _source = Symbol('_source');
   let UnmodifiableListView$ = dart.generic(function(E) {
     class UnmodifiableListView extends _internal.UnmodifiableListBase$(E) {
       UnmodifiableListView(source) {
         this[_source] = source;
       }
       get [core.$length]() {
@@ skipping 2841 matching lines @@
     class _TypeTest extends core.Object {
       test(v) {
         return dart.is(v, T);
       }
     }
     return _TypeTest;
   });
   let _TypeTest = _TypeTest$();
   let _comparator = Symbol('_comparator');
   let _validKey = Symbol('_validKey');
-  let _internal = Symbol('_internal');
+  let _internal$ = Symbol('_internal');
   let SplayTreeMap$ = dart.generic(function(K, V) {
     class SplayTreeMap extends _SplayTree$(K) {
       SplayTreeMap(compare, isValidKey) {
         if (compare === void 0)
           compare = null;
         if (isValidKey === void 0)
           isValidKey = null;
         this[_comparator] = dart.as(compare == null ? core.Comparable.compare : compare, core.Comparator$(K));
         this[_validKey] = dart.as(isValidKey != null ? isValidKey : v => dart.is(v, K), _Predicate);
         super._SplayTree();
@@ skipping 23 matching lines @@
           compare = null;
         if (isValidKey === void 0)
           isValidKey = null;
         let map = new (SplayTreeMap$(K, V))(compare, isValidKey);
         Maps[_fillMapWithIterables](map, keys, values);
         return map;
       }
       [_compare](key1, key2) {
         return this[_comparator](key1, key2);
       }
-      [_internal]() {
+      [_internal$]() {
         this[_comparator] = null;
         this[_validKey] = null;
         super._SplayTree();
       }
       get(key) {
         if (key == null)
           throw new core.ArgumentError(key);
         if (!dart.notNull(dart.dcall(this[_validKey], key)))
           return null;
         if (this[_root] != null) {
@@ skipping 140 matching lines @@
         while (node.left != null) {
           node = node.left;
         }
         return node.key;
       }
     }
     SplayTreeMap[dart.implements] = () => [core.Map$(K, V)];
     dart.defineNamedConstructor(SplayTreeMap, 'from');
     dart.defineNamedConstructor(SplayTreeMap, 'fromIterable');
     dart.defineNamedConstructor(SplayTreeMap, 'fromIterables');
-    dart.defineNamedConstructor(SplayTreeMap, _internal);
+    dart.defineNamedConstructor(SplayTreeMap, _internal$);
     return SplayTreeMap;
   });
   let SplayTreeMap = SplayTreeMap$();
   let _workList = Symbol('_workList');
   let _tree = Symbol('_tree');
   let _currentNode = Symbol('_currentNode');
   let _findLeftMostDescendent = Symbol('_findLeftMostDescendent');
   let _getValue = Symbol('_getValue');
   let _rebuildWorkList = Symbol('_rebuildWorkList');
   let _SplayTreeIterator$ = dart.generic(function(T) {
@@ skipping 1929 matching lines @@
   exports.LinkedHashMapKeyIterable$ = LinkedHashMapKeyIterable$;
   exports.LinkedHashMapKeyIterable = LinkedHashMapKeyIterable;
   exports.LinkedHashMapKeyIterator$ = LinkedHashMapKeyIterator$;
   exports.LinkedHashMapKeyIterator = LinkedHashMapKeyIterator;
   exports.HashSetIterator$ = HashSetIterator$;
   exports.HashSetIterator = HashSetIterator;
   exports.LinkedHashSetCell = LinkedHashSetCell;
   exports.LinkedHashSetIterator$ = LinkedHashSetIterator$;
   exports.LinkedHashSetIterator = LinkedHashSetIterator;
 })(collection || (collection = {}));