Remove DartString from constants.

pkg/compiler/lib/src/js_backend/constant_system_javascript.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.
 
 library dart2js.constant_system.js;
 
 import '../constant_system_dart.dart';
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../common_elements.dart' show CommonElements;
 import '../elements/types.dart';
 import '../elements/entities.dart';
-import '../tree/dartstring.dart' show DartString, LiteralDartString;
 
 const JAVA_SCRIPT_CONSTANT_SYSTEM = const JavaScriptConstantSystem();
 
 class JavaScriptBitNotOperation extends BitNotOperation {
   const JavaScriptBitNotOperation();
 
   ConstantValue fold(ConstantValue constant) {
     if (JAVA_SCRIPT_CONSTANT_SYSTEM.isInt(constant)) {
       // In JavaScript we don't check for -0 and treat it as if it was zero.
       if (constant.isMinusZero) constant = DART_CONSTANT_SYSTEM.createInt(0);
@@ skipping 272 matching lines @@
   }
 
   @override
   NumConstantValue createInt(int i) {
     return convertToJavaScriptConstant(new IntConstantValue(i));
   }
 
   NumConstantValue createInt32(int i) => new IntConstantValue(i & BITS32);
   NumConstantValue createDouble(double d) =>
       convertToJavaScriptConstant(new DoubleConstantValue(d));
-  StringConstantValue createString(DartString string) {
+  StringConstantValue createString(String string) {
     return new StringConstantValue(string);
   }
 
   BoolConstantValue createBool(bool value) => new BoolConstantValue(value);
   NullConstantValue createNull() => new NullConstantValue();
 
   @override
   ListConstantValue createList(InterfaceType type, List<ConstantValue> values) {
     return new ListConstantValue(type, values);
   }
@@ skipping 67 matching lines @@
     InterfaceType type = commonElements.getConstantMapTypeFor(sourceType,
         hasProtoKey: hasProtoKey, onlyStringKeys: onlyStringKeys);
     return new JavaScriptMapConstant(
         type, keysList, values, protoValue, onlyStringKeys);
   }
 
   @override
   ConstantValue createSymbol(CommonElements commonElements, String text) {
     InterfaceType type = commonElements.symbolImplementationType;
     FieldEntity field = commonElements.symbolField;
-    ConstantValue argument = createString(new DartString.literal(text));
+    ConstantValue argument = createString(text);
     // TODO(johnniwinther): Use type arguments when all uses no longer expect
     // a [FieldElement].
     Map<FieldEntity, ConstantValue> fields = /*<FieldElement, ConstantValue>*/ {
       field: argument
     };
     return new ConstructedConstantValue(type, fields);
   }
 }
 
 class JavaScriptMapConstant extends MapConstantValue {
   /**
    * The [PROTO_PROPERTY] must not be used as normal property in any JavaScript
    * object. It would change the prototype chain.
    */
-  static const LiteralDartString PROTO_PROPERTY =
-      const LiteralDartString("__proto__");
+  static const String PROTO_PROPERTY = "__proto__";
 
   /** The dart class implementing constant map literals. */
   static const String DART_CLASS = "ConstantMap";
   static const String DART_STRING_CLASS = "ConstantStringMap";
   static const String DART_PROTO_CLASS = "ConstantProtoMap";
   static const String DART_GENERAL_CLASS = "GeneralConstantMap";
   static const String LENGTH_NAME = "_length";
   static const String JS_OBJECT_NAME = "_jsObject";
   static const String KEYS_NAME = "_keys";
   static const String PROTO_VALUE = "_protoValue";
@@ skipping 15 matching lines @@
       result.add(keyList);
     } else {
       // Add the keys individually to avoid generating an unused list constant
       // for the keys.
       result.addAll(keys);
     }
     result.addAll(values);
     return result;
   }
 }