js_ast: implement rest/spread parsing

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>
@@ skipping 1183 matching lines @@
                                                    ^^
 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 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 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;
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^