Work around runtime engine deficiencies.

sdk/lib/_internal/compiler/implementation/js_backend/constant_emitter.dart

 // Copyright (c) 2012, 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.
 
 part of js_backend;
 
 class ConstantEmitter  {
   ConstantReferenceEmitter _referenceEmitter;
   ConstantInitializerEmitter _initializerEmitter;
 
@@ skipping 281 matching lines @@
   }
 
   jsAst.Expression visitInterceptor(InterceptorConstant constant) {
     return new jsAst.PropertyAccess.field(
         new jsAst.VariableUse(
             getJsConstructor(constant.dispatchedType.element)),
         'prototype');
   }
 
   jsAst.Expression visitConstructed(ConstructedConstant constant) {
+    Element element = constant.type.element;
+    if (element.isForeign(compiler)
+        && element.name == const SourceString('JS_CONST')) {
+      StringConstant str = constant.fields[0];
+      return new jsAst.LiteralExpression(str.value.slowToString());
+    }
     jsAst.New instantiation = new jsAst.New(
         new jsAst.VariableUse(getJsConstructor(constant.type.element)),
         _array(constant.fields));
     return maybeAddTypeArguments(constant.type, instantiation);
   }
 
   List<jsAst.Expression> _array(List<Constant> values) {
     List<jsAst.Expression> valueList = <jsAst.Expression>[];
     for (int i = 0; i < values.length; i++) {
       valueList.add(_reference(values[i]));
@@ skipping 12 matching lines @@
           .toList(growable: false)
           .map((DartType type) => rti.getTypeRepresentation(type, (_){}));
       jsAst.Expression argumentList =
           new jsAst.LiteralString('[${arguments.join(', ')}]');
       return new jsAst.Call(getHelperProperty(backend.getSetRuntimeTypeInfo()),
                             [value, argumentList]);
     }
     return value;
   }
 }