Use an enum in embedded_names as input to JS_GET_NAME.

pkg/compiler/lib/src/ssa/builder.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 ssa;
 
 class SsaFunctionCompiler implements FunctionCompiler {
   SsaCodeGeneratorTask generator;
   SsaBuilderTask builder;
   SsaOptimizerTask optimizer;
@@ skipping 3720 matching lines @@
       argument = arguments[0];
       break;
     default:
       for (int i = 1; i < arguments.length; i++) {
         compiler.reportError(
             arguments[i], MessageKind.GENERIC,
             {'text': 'Error: Extra argument to JS_GET_NAME.'});
       }
       return;
     }
-    ast.LiteralString string = argument.asLiteralString();
-    if (string == null) {
+    Element element = elements[argument];
+    if (element == null ||
+        element is! FieldElement ||
+        element.enclosingClass != backend.jsGetNameEnum) {
       compiler.reportError(
           argument, MessageKind.GENERIC,
-          {'text': 'Error: Expected a literal string.'});
+          {'text': 'Error: Expected a JsGetName enum value.'});
     }
+    EnumClassElement enumClass = element.enclosingClass;
+    int index = enumClass.enumValues.indexOf(element);
     stack.add(
         addConstantString(
             backend.namer.getNameForJsGetName(
-                argument, string.dartString.slowToString())));
+                argument, JsGetName.values[index])));
   }
 
   void handleForeignJsEmbeddedGlobal(ast.Send node) {
     List<ast.Node> arguments = node.arguments.toList();
     ast.Node globalNameNode;
     switch (arguments.length) {
     case 0:
     case 1:
       compiler.reportError(
           node, MessageKind.GENERIC,
@@ skipping 3154 matching lines @@
     if (unaliased is TypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(DynamicType type, SsaBuilder builder) {
     JavaScriptBackend backend = builder.compiler.backend;
     ClassElement cls = backend.findHelper('DynamicRuntimeType');
     builder.push(new HDynamicType(type, new TypeMask.exact(cls, classWorld)));
   }
 }