allow JS builtin to be typed as needed

lib/src/codegen/reify_coercions.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dev_compiler.src.codegen.reify_coercions;
 
 import 'package:analyzer/analyzer.dart' as analyzer;
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/type_system.dart'
     show StrongTypeSystemImpl;
 import 'package:logging/logging.dart' as logger;
 
 import '../info.dart';
+import '../utils.dart' show isInlineJS;
 
 import 'ast_builder.dart';
 
 final _log = new logger.Logger('dev_compiler.reify_coercions');
 
 // TODO(leafp) Factor this out or use an existing library
 class Tuple2<T0, T1> {
   final T0 e0;
   final T1 e1;
   Tuple2(this.e0, this.e1);
@@ skipping 136 matching lines @@
   // The main entry point.  Coerce e using c, returning a new expression,
   // possibly recording additional coercions functions and typedefs to
   // be discharged at a higher level.
   Expression coerceExpression(Expression e, Coercion c) {
     assert(c != null);
     assert(c is! CoercionError);
     if (e is NamedExpression) {
       Expression inner = coerceExpression(e.expression, c);
       return new NamedExpression(e.name, inner);
     }
+    if (e is MethodInvocation && isInlineJS(e.methodName.staticElement)) {
+      // Inline JS code should not need casts.
+      return e;
+    }
     if (c is Cast) return _castExpression(e, c);
     assert(c is Identity);
     return e;
   }
 
   ///////////////// Private //////////////////////////////////
 
   Expression _castExpression(Expression e, Cast c) {
     var ttName = _tm.typeNameFromDartType(c.toType);
     var cast = AstBuilder.asExpression(e, ttName);
@@ skipping 274 matching lines @@
     var t = _mkNewTypeName(dType, id, args);
     return t;
   }
 
   TypeName _mkNewTypeName(DartType type, Identifier id, List<TypeName> args) {
     var t = AstBuilder.typeName(id, args);
     t.type = type;
     return t;
   }
 }