fixes #168, dart:js implementation with a test

tool/sdk_expected_errors.txt

-severe: line 90, column 1 of dart:js: [Message] File dart:html not found
-import 'dart:html' show Blob, Event, ImageData, Node, Window;
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-severe: line 92, column 1 of dart:js: [Message] File dart:indexed_db not found
-import 'dart:indexed_db' show KeyRange;
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 168, column 14 of dart:isolate: [DownCastComposite] IsolateNatives.spawnFunction(entryPoint, message, paused).then((msg) => new Isolate(msg[1], pauseCapability: msg[2], terminateCapability: msg[3])) (Future<dynamic>) will need runtime check to cast to type Future<Isolate>
       return IsolateNatives.spawnFunction(entryPoint, message, paused)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 234, column 14 of dart:isolate: [DownCastComposite] IsolateNatives.spawnUri(uri, args, message, paused).then((msg) => new Isolate(msg[1], pauseCapability: msg[2], terminateCapability: msg[3])) (Future<dynamic>) will need runtime check to cast to type Future<Isolate>
       return IsolateNatives.spawnUri(uri, args, message, paused)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 426, column 16 of dart:math: [DownCastImplicit] rnd32.remainder(max) (num) will need runtime check to cast to type int
       result = rnd32.remainder(max); // % max;
                ^^^^^^^^^^^^^^^^^^^^
 warning: line 37, column 25 of dart:math/point.dart: [DownCastComposite] x + other.x (num) will need runtime check to cast to type T
@@ skipping 127 matching lines @@
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 420, column 44 of dart:_interceptors/js_number.dart: [AnalyzerMessage] Classes cannot implement 'double'
 class JSDouble extends JSNumber implements double {
                                            ^^^^^^
 warning: line 349, column 41 of dart:_interceptors/js_number.dart: [AnalyzerMessage] Classes cannot implement 'int'
 class JSInt extends JSNumber implements int, double {
                                         ^^^
 warning: line 16, column 47 of dart:_interceptors/js_number.dart: [AnalyzerMessage] Classes cannot implement 'num'
 class JSNumber extends Interceptor implements num {
                                               ^^^
+severe: line 110, column 17 of dart:_interceptors/js_number.dart: [AnalyzerMessage] The return type 'JSNumber' is not a 'double', as defined by the method 'toDouble'
+  toDouble() => this;
+                ^^^^
 warning: line 349, column 46 of dart:_interceptors/js_number.dart: [AnalyzerMessage] Classes cannot implement 'double'
 class JSInt extends JSNumber implements int, double {
                                              ^^^^^^
-severe: line 110, column 17 of dart:_interceptors/js_number.dart: [AnalyzerMessage] The return type 'JSNumber' is not a 'double', as defined by the method 'toDouble'
-  toDouble() => this;
-                ^^^^
 warning: line 83, column 28 of dart:_interceptors/js_number.dart: [DownCastImplicit] JS('num', r'Math.ceil(#)', this) (num) will need runtime check to cast to type double
   double ceilToDouble() => JS('num', r'Math.ceil(#)', this);
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 85, column 29 of dart:_interceptors/js_number.dart: [DownCastImplicit] JS('num', r'Math.floor(#)', this) (num) will need runtime check to cast to type double
   double floorToDouble() => JS('num', r'Math.floor(#)', this);
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 89, column 14 of dart:_interceptors/js_number.dart: [DownCastImplicit] JS('num', r'-Math.round(-#)', this) (num) will need runtime check to cast to type double
       return JS('num', r'-Math.round(-#)', this);
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 91, column 14 of dart:_interceptors/js_number.dart: [DownCastImplicit] JS('num', r'Math.round(#)', this) (num) will need runtime check to cast to type double
@@ skipping 91 matching lines @@
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 311, column 9 of dart:_native_typed_data: [DownCastImplicit] _storage.sublist(start * 4, end * 4) (List<int>) will need runtime check to cast to type Int32List
         _storage.sublist(start * 4, end * 4));
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 415, column 9 of dart:_native_typed_data: [DownCastImplicit] _storage.sublist(start * 2, end * 2) (List<double>) will need runtime check to cast to type NativeFloat64List
         _storage.sublist(start * 2, end * 2));
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 1106, column 12 of dart:_native_typed_data: [DownCastImplicit] length == null ? _create2(buffer, offsetInBytes) : _create3(buffer, offsetInBytes, length) (Int8List) will need runtime check to cast to type NativeInt8List
     return length == null
            ^^^^^^^^^^^^^^^
-warning: line 576, column 29 of dart:_isolate_helper: [DownCastComposite] doneHandlers (dynamic) will need runtime check to cast to type Iterable<SendPort>
+warning: line 574, column 29 of dart:_isolate_helper: [DownCastComposite] doneHandlers (dynamic) will need runtime check to cast to type Iterable<SendPort>
       for (SendPort port in doneHandlers) {
                             ^^^^^^^^^^^^
-warning: line 835, column 37 of dart:_isolate_helper: [DownCastComposite] args (dynamic) will need runtime check to cast to type List<String>
+warning: line 833, column 37 of dart:_isolate_helper: [DownCastComposite] args (dynamic) will need runtime check to cast to type List<String>
           _startIsolate(entryPoint, args, message,
                                     ^^^^
-warning: line 882, column 11 of dart:_isolate_helper: [DownCastComposite] msg['args'] (dynamic) will need runtime check to cast to type List<String>
+warning: line 880, column 11 of dart:_isolate_helper: [DownCastComposite] msg['args'] (dynamic) will need runtime check to cast to type List<String>
           msg['args'], msg['msg'],
           ^^^^^^^^^^^
 warning: line 89, column 38 of dart:_isolate_helper/isolate_serialization.dart: [DownCastImplicit] indexable (JSIndexable) will need runtime check to cast to type JSArray<dynamic>
     List serialized = serializeArray(indexable);
                                      ^^^^^^^^^
 warning: line 120, column 24 of dart:_isolate_helper/isolate_serialization.dart: [DownCastImplicit] serializeTearOff (Function) will need runtime check to cast to type (dynamic) → dynamic
             x.keys.map(serializeTearOff).toList(),
                        ^^^^^^^^^^^^^^^^
 warning: line 121, column 26 of dart:_isolate_helper/isolate_serialization.dart: [DownCastImplicit] serializeTearOff (Function) will need runtime check to cast to type (dynamic) → dynamic
             x.values.map(serializeTearOff).toList()];
@@ skipping 18 matching lines @@
                             ^^^^^^
 warning: line 20, column 39 of dart:async/async_error.dart: [DownCastImplicit] errorHandler (Function) will need runtime check to cast to type (dynamic) → dynamic
     return zone.registerUnaryCallback(errorHandler);
                                       ^^^^^^^^^^^^
 severe: line 208, column 22 of dart:async/broadcast_stream_controller.dart: [AnalyzerMessage] The getter '_isFiring' is not defined for the class 'StreamSubscription<T>'
     if (subscription._isFiring) {
                      ^^^^^^^^^
 severe: line 206, column 32 of dart:async/broadcast_stream_controller.dart: [AnalyzerMessage] The getter '_next' is not defined for the class 'StreamSubscription<T>'
     if (identical(subscription._next, subscription)) return null;
                                ^^^^^
+severe: line 207, column 36 of dart:async/broadcast_stream_controller.dart: [AnalyzerMessage] The getter '_next' is not defined for the class 'StreamSubscription<T>'
+    assert(!identical(subscription._next, subscription));
+                                   ^^^^^
 severe: line 209, column 20 of dart:async/broadcast_stream_controller.dart: [AnalyzerMessage] The method '_setRemoveAfterFiring' is not defined for the class 'StreamSubscription<T>'
       subscription._setRemoveAfterFiring();
                    ^^^^^^^^^^^^^^^^^^^^^
-severe: line 207, column 36 of dart:async/broadcast_stream_controller.dart: [AnalyzerMessage] The getter '_next' is not defined for the class 'StreamSubscription<T>'
-    assert(!identical(subscription._next, subscription));
-                                   ^^^^^
 severe: line 211, column 38 of dart:async/broadcast_stream_controller.dart: [AnalyzerMessage] The getter '_next' is not defined for the class 'StreamSubscription<T>'
       assert(!identical(subscription._next, subscription));
                                      ^^^^^
 warning: line 8, column 67 of dart:async/broadcast_stream_controller.dart: [DownCastComposite] controller (_StreamControllerLifecycle<dynamic>) will need runtime check to cast to type _StreamControllerLifecycle<T>
   _BroadcastStream(_StreamControllerLifecycle controller) : super(controller);
                                                                   ^^^^^^^^^^
 warning: line 36, column 15 of dart:async/broadcast_stream_controller.dart: [DownCastComposite] controller (_StreamControllerLifecycle<dynamic>) will need runtime check to cast to type _StreamControllerLifecycle<T>
       : super(controller, onData, onError, onDone, cancelOnError) {
               ^^^^^^^^^^
 warning: line 40, column 52 of dart:async/broadcast_stream_controller.dart: [DownCastComposite] super._controller (_StreamControllerLifecycle<T>) will need runtime check to cast to type _BroadcastStreamController<T>
@@ skipping 73 matching lines @@
                                                      ^^^^^^^^^^^^^
 warning: line 66, column 61 of dart:async/schedule_microtask.dart: [DownCastComposite] callback (dynamic) will need runtime check to cast to type () → void
     _nextCallback = _lastCallback = new _AsyncCallbackEntry(callback);
                                                             ^^^^^^^^
 warning: line 71, column 60 of dart:async/schedule_microtask.dart: [DownCastComposite] callback (dynamic) will need runtime check to cast to type () → void
     _AsyncCallbackEntry newEntry = new _AsyncCallbackEntry(callback);
                                                            ^^^^^^^^
 warning: line 84, column 55 of dart:async/schedule_microtask.dart: [DownCastComposite] callback (dynamic) will need runtime check to cast to type () → void
   _AsyncCallbackEntry entry = new _AsyncCallbackEntry(callback);
                                                       ^^^^^^^^
+severe: line 321, column 34 of dart:async/stream.dart: [AnalyzerMessage] The getter '_addError' is not defined for the class 'StreamController'
+      final addError = eventSink._addError;
+                                 ^^^^^^^^^
 severe: line 1227, column 17 of dart:async/stream.dart: [AnalyzerMessage] The method '_addError' is not defined for the class 'StreamController'
       eventSink._addError(error, stackTrace);  // Avoid Zone error replacement.
                 ^^^^^^^^^
 severe: line 396, column 30 of dart:async/stream.dart: [AnalyzerMessage] The getter '_addError' is not defined for the class 'StreamController'
           onError: eventSink._addError,  // Avoid Zone error replacement.
                              ^^^^^^^^^
-severe: line 321, column 34 of dart:async/stream.dart: [AnalyzerMessage] The getter '_addError' is not defined for the class 'StreamController'
-      final addError = eventSink._addError;
-                                 ^^^^^^^^^
 warning: line 90, column 25 of dart:async/stream.dart: [DownCastComposite] value (dynamic) will need runtime check to cast to type T
         controller._add(value);
                         ^^^^^
 warning: line 217, column 41 of dart:async/stream.dart: [DownCastComposite] mapSink ((EventSink<T>) → EventSink<dynamic>) will need runtime check to cast to type (EventSink<dynamic>) → EventSink
     return new _BoundSinkStream(source, mapSink);
                                         ^^^^^^^
 warning: line 249, column 44 of dart:async/stream.dart: [DownCastComposite] onListen ((StreamSubscription<T>) → void) will need runtime check to cast to type (StreamSubscription<dynamic>) → void
     return new _AsBroadcastStream<T>(this, onListen, onCancel);
                                            ^^^^^^^^
 warning: line 249, column 54 of dart:async/stream.dart: [DownCastComposite] onCancel ((StreamSubscription<T>) → void) will need runtime check to cast to type (StreamSubscription<dynamic>) → void
@@ skipping 676 matching lines @@
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 warning: line 140, column 43 of dart:_js_helper/regexp_helper.dart: [DownCastComposite] match (List<dynamic>) will need runtime check to cast to type List<String>
     return new _MatchImplementation(this, match);
                                           ^^^^^
 warning: line 152, column 43 of dart:_js_helper/regexp_helper.dart: [DownCastComposite] match (List<dynamic>) will need runtime check to cast to type List<String>
     return new _MatchImplementation(this, match);
                                           ^^^^^
 warning: line 137, column 23 of dart:_js_helper/string_helper.dart: [DownCastComposite] pattern.allMatches(receiver) (dynamic) will need runtime check to cast to type Iterable<Match>
   for (Match match in pattern.allMatches(receiver)) {
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-severe: line 514, column 46 of dart:js: [AnalyzerMessage] The name 'Window' is not defined and cannot be used in an 'is' expression
-      || o is Node || o is TypedData || o is Window) {
-                                             ^^^^^^
-severe: line 553, column 46 of dart:js: [AnalyzerMessage] The name 'Window' is not defined and cannot be used in an 'is' expression
-      || o is Node || o is TypedData || o is Window)) {
-                                             ^^^^^^
-severe: line 467, column 5 of dart:js: [AnalyzerMessage] Undefined name 'getIsolateAffinityTag'
-    getIsolateAffinityTag(r'_$dart_dartClosure');
-    ^^^^^^^^^^^^^^^^^^^^^
-severe: line 552, column 60 of dart:js: [AnalyzerMessage] The name 'ImageData' is not defined and cannot be used in an 'is' expression
-      && (o is Blob || o is Event || o is KeyRange || o is ImageData
-                                                           ^^^^^^^^^
-severe: line 513, column 63 of dart:js: [AnalyzerMessage] The name 'ImageData' is not defined and cannot be used in an 'is' expression
-  } else if (o is Blob || o is Event || o is KeyRange || o is ImageData
-                                                              ^^^^^^^^^
-severe: line 465, column 5 of dart:js: [AnalyzerMessage] Undefined name 'getIsolateAffinityTag'
-    getIsolateAffinityTag(r'_$dart_dartObject');
-    ^^^^^^^^^^^^^^^^^^^^^
-severe: line 514, column 15 of dart:js: [AnalyzerMessage] The name 'Node' is not defined and cannot be used in an 'is' expression
-      || o is Node || o is TypedData || o is Window) {
-              ^^^^
-severe: line 553, column 15 of dart:js: [AnalyzerMessage] The name 'Node' is not defined and cannot be used in an 'is' expression
-      || o is Node || o is TypedData || o is Window)) {
-              ^^^^
-severe: line 513, column 32 of dart:js: [AnalyzerMessage] The name 'Event' is not defined and cannot be used in an 'is' expression
-  } else if (o is Blob || o is Event || o is KeyRange || o is ImageData
-                               ^^^^^
-severe: line 552, column 29 of dart:js: [AnalyzerMessage] The name 'Event' is not defined and cannot be used in an 'is' expression
-      && (o is Blob || o is Event || o is KeyRange || o is ImageData
-                            ^^^^^
-warning: line 449, column 29 of dart:js: [AnalyzerMessage] Local variables cannot be referenced before they are declared
-    _checkRange(start, end, length);
-                            ^^^^^^
-severe: line 465, column 5 of dart:js: [AnalyzerMessage] The function 'getIsolateAffinityTag' is not defined
-    getIsolateAffinityTag(r'_$dart_dartObject');
-    ^^^^^^^^^^^^^^^^^^^^^
-severe: line 552, column 43 of dart:js: [AnalyzerMessage] The name 'KeyRange' is not defined and cannot be used in an 'is' expression
-      && (o is Blob || o is Event || o is KeyRange || o is ImageData
-                                          ^^^^^^^^
-severe: line 513, column 46 of dart:js: [AnalyzerMessage] The name 'KeyRange' is not defined and cannot be used in an 'is' expression
-  } else if (o is Blob || o is Event || o is KeyRange || o is ImageData
-                                             ^^^^^^^^
-severe: line 467, column 5 of dart:js: [AnalyzerMessage] The function 'getIsolateAffinityTag' is not defined
-    getIsolateAffinityTag(r'_$dart_dartClosure');
-    ^^^^^^^^^^^^^^^^^^^^^
-severe: line 552, column 16 of dart:js: [AnalyzerMessage] The name 'Blob' is not defined and cannot be used in an 'is' expression
-      && (o is Blob || o is Event || o is KeyRange || o is ImageData
-               ^^^^
-severe: line 513, column 19 of dart:js: [AnalyzerMessage] The name 'Blob' is not defined and cannot be used in an 'is' expression
-  } else if (o is Blob || o is Event || o is KeyRange || o is ImageData
-                  ^^^^
-warning: line 90, column 8 of dart:js: [AnalyzerMessage] Target of URI does not exist: 'dart:html'
-import 'dart:html' show Blob, Event, ImageData, Node, Window;
-       ^^^^^^^^^^^
-warning: line 92, column 8 of dart:js: [AnalyzerMessage] Target of URI does not exist: 'dart:indexed_db'
-import 'dart:indexed_db' show KeyRange;
-       ^^^^^^^^^^^^^^^^^
-warning: line 357, column 44 of dart:js: [DownCastComposite] _convertToJS ((dynamic) → dynamic) will need runtime check to cast to type (E) → dynamic
+warning: line 325, column 44 of dart:js: [DownCastComposite] _convertToJS ((dynamic) → dynamic) will need runtime check to cast to type (E) → dynamic
       : super._fromJs([]..addAll(other.map(_convertToJS)));
                                            ^^^^^^^^^^^^
-warning: line 390, column 12 of dart:js: [DownCastComposite] super[index] (dynamic) will need runtime check to cast to type E
+warning: line 358, column 12 of dart:js: [DownCastComposite] super[index] (dynamic) will need runtime check to cast to type E
     return super[index];
            ^^^^^^^^^^^^
-warning: line 425, column 24 of dart:js: [DownCastImplicit] list (Object) will need runtime check to cast to type List<dynamic>
+warning: line 394, column 24 of dart:js: [DownCastImplicit] list (Object) will need runtime check to cast to type List<dynamic>
     callMethod('push', list);
                        ^^^^
-warning: line 435, column 12 of dart:js: [DownCastComposite] callMethod('splice', [index, 1])[0] (dynamic) will need runtime check to cast to type E
+warning: line 404, column 12 of dart:js: [DownCastComposite] callMethod('splice', [index, 1])[0] (dynamic) will need runtime check to cast to type E
     return callMethod('splice', [index, 1])[0];
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-warning: line 440, column 12 of dart:js: [DownCastComposite] callMethod('pop') (dynamic) will need runtime check to cast to type E
+warning: line 409, column 12 of dart:js: [DownCastComposite] callMethod('pop') (dynamic) will need runtime check to cast to type E
     return callMethod('pop');
            ^^^^^^^^^^^^^^^^^
-warning: line 558, column 52 of dart:js: [DownCastImplicit] ms (num) will need runtime check to cast to type int
+warning: line 486, column 52 of dart:js: [DownCastImplicit] ms (num) will need runtime check to cast to type int
     return new DateTime.fromMillisecondsSinceEpoch(ms);
                                                    ^^
-warning: line 568, column 12 of dart:js: [DownCastImplicit] _getDartProxy(o, _DART_CLOSURE_PROPERTY_NAME, (o) => new JsFunction._fromJs(o)) (Object) will need runtime check to cast to type JsObject
-    return _getDartProxy(o, _DART_CLOSURE_PROPERTY_NAME,
-           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-warning: line 571, column 12 of dart:js: [DownCastImplicit] _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME, (o) => new JsArray._fromJs(o)) (Object) will need runtime check to cast to type JsObject
-    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
-           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-warning: line 574, column 12 of dart:js: [DownCastImplicit] _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME, (o) => new JsObject._fromJs(o)) (Object) will need runtime check to cast to type JsObject
-    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
-           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 severe: line 120, column 7 of dart:_js_mirrors: [AnalyzerMessage] Missing concrete implementation of getter 'TypeMirror.typeArguments', getter 'TypeMirror.isOriginalDeclaration', getter 'DeclarationMirror.owner', getter 'DeclarationMirror.location' and 10 more
 class JsTypeMirror implements TypeMirror {
       ^^^^^^^^^^^^
 severe: line 47, column 7 of dart:_js_mirrors: [AnalyzerMessage] Missing concrete implementation of getter 'InstanceMirror.type', getter 'InstanceMirror.hasReflectee' and 'InstanceMirror.delegate'
 class JsInstanceMirror implements InstanceMirror {
       ^^^^^^^^^^^^^^^^
 severe: line 126, column 7 of dart:_js_mirrors: [AnalyzerMessage] Missing concrete implementation of getter 'VariableMirror.isStatic', getter 'VariableMirror.isFinal', getter 'DeclarationMirror.owner', getter 'ParameterMirror.isOptional' and 9 more
 class JsParameterMirror implements ParameterMirror {
       ^^^^^^^^^^^^^^^^^
 severe: line 84, column 7 of dart:_js_mirrors: [AnalyzerMessage] Missing concrete implementation of getter 'TypeMirror.typeArguments', getter 'ClassMirror.superinterfaces', getter 'TypeMirror.isOriginalDeclaration', getter 'ClassMirror.staticMembers' and 19 more
 class JsClassMirror implements ClassMirror {
       ^^^^^^^^^^^^^
 severe: line 134, column 7 of dart:_js_mirrors: [AnalyzerMessage] Missing concrete implementation of getter 'MethodMirror.isSetter', getter 'MethodMirror.isConstructor', getter 'MethodMirror.isConstConstructor', getter 'MethodMirror.isAbstract' and 17 more
 class JsMethodMirror implements MethodMirror {
       ^^^^^^^^^^^^^^
 severe: line 61, column 35 of dart:_js_mirrors: [AnalyzerMessage] The argument type 'void' cannot be assigned to the parameter type 'Object'
     return new JsInstanceMirror._(field);
                                   ^^^^^
 warning: line 171, column 10 of dart:mirrors: [DownCastImplicit] (tm as ClassMirror).originalDeclaration (TypeMirror) will need runtime check to cast to type ClassMirror
   return (tm as ClassMirror).originalDeclaration;
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^