Convert dart_utils.js to input_sdk/lib/_internal/utils.dart (#310)

test/codegen/expect/collection/wrappers.js

 dart_library.library('collection/wrappers', null, /* Imports */[
   "dart/_runtime",
   'collection/src/canonicalized_map',
   'dart/core',
   'dart/math',
   'dart/collection'
 ], /* Lazy imports */[
   'collection/src/unmodifiable_wrappers'
 ], function(exports, dart, canonicalized_map, core, math, collection, unmodifiable_wrappers) {
   'use strict';
   let dartx = dart.dartx;
-  dart.export(exports, canonicalized_map);
-  dart.export(exports, unmodifiable_wrappers);
+  dart.export_(exports, canonicalized_map);
+  dart.export_(exports, unmodifiable_wrappers);
   let _base = Symbol('_base');
   let _DelegatingIterableBase$ = dart.generic(function(E) {
     class _DelegatingIterableBase extends core.Object {
       _DelegatingIterableBase() {
       }
       any(test) {
         dart.as(test, dart.functionType(core.bool, [E]));
         return this[_base][dartx.any](test);
       }
       contains(element) {
@@ skipping 669 matching lines @@
       toString() {
         return dart.toString(this.toSet());
       }
       add(value) {
         dart.as(value, V);
         let key = dart.as(dart.dcall(this[_keyForValue], value), K);
         let result = false;
         this[_baseMap].putIfAbsent(key, dart.as(dart.fn(() => {
           result = true;
           return value;
-        }), __CastType0));
+        }), __CastType0$(V)));
         return result;
       }
       addAll(elements) {
         dart.as(elements, core.Iterable$(V));
         return elements[dartx.forEach](dart.bind(this, 'add'));
       }
       clear() {
         return this[_baseMap].clear();
       }
       containsAll(other) {
@@ skipping 102 matching lines @@
   exports.DelegatingSet$ = DelegatingSet$;
   exports.DelegatingSet = DelegatingSet;
   exports.DelegatingQueue$ = DelegatingQueue$;
   exports.DelegatingQueue = DelegatingQueue;
   exports.DelegatingMap$ = DelegatingMap$;
   exports.DelegatingMap = DelegatingMap;
   exports.MapKeySet$ = MapKeySet$;
   exports.MapValueSet$ = MapValueSet$;
   exports.MapValueSet = MapValueSet;
 });