Use elements/types in constants/values

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 '../compiler.dart' show Compiler;
 import '../constant_system_dart.dart';
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
@@ skipping 302 matching lines @@
   NullConstantValue createNull() => new NullConstantValue();
 
   @override
   ListConstantValue createList(
       ResolutionInterfaceType type, List<ConstantValue> values) {
     return new ListConstantValue(type, values);
   }
 
   @override
   ConstantValue createType(Compiler compiler, ResolutionDartType type) {
-    return new TypeConstantValue(
-        type,
-        compiler.backend.backendClasses.typeImplementation
-            .computeType(compiler.resolution));
+    ResolutionInterfaceType instanceType = compiler
+        .backend.backendClasses.typeImplementation
+        .computeType(compiler.resolution);
+    return new TypeConstantValue(type, instanceType);
   }
 
   // Integer checks report true for -0.0, INFINITY, and -INFINITY.  At
   // runtime an 'X is int' check is implemented as:
   //
   // typeof(X) === "number" && Math.floor(X) === X
   //
   // We consistently match that runtime semantics at compile time as well.
   bool isInt(ConstantValue constant) {
     return constant.isInt ||
@@ skipping 38 matching lines @@
         }
       } else {
         onlyStringKeys = false;
         // Don't handle __proto__ values specially in the general map case.
         protoValue = null;
         break;
       }
     }
 
     bool hasProtoKey = (protoValue != null);
-    ResolutionDartType keysType;
+    ResolutionInterfaceType keysType;
     if (sourceType.treatAsRaw) {
       keysType = commonElements.listType();
     } else {
       keysType = commonElements.listType(sourceType.typeArguments.first);
     }
     ListConstantValue keysList = new ListConstantValue(keysType, keys);
     ClassElement classElement = onlyStringKeys
         ? (hasProtoKey
             ? backend.helpers.constantProtoMapClass
             : backend.helpers.constantStringMapClass)
@@ skipping 62 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;
   }
 }