Rename Constant to ConstantValue and ConstExp to ConstantExpression.

tests/compiler/dart2js/deferred_follow_constant_dependencies_test.dart

 // Copyright (c) 2014, 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.
 
 // Test that constants depended on by other constants are correctly deferred.
 
 import 'dart:async';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/implementation/constants/values.dart';
 import 'package:expect/expect.dart';
@@ skipping 21 matching lines @@
                                    packageRoot,
                                    [],
                                    {});
   asyncTest(() => compiler.run(Uri.parse('memory:main.dart')).then((_) {
     var outputUnitForElement = compiler.deferredLoadTask.outputUnitForElement;
     var outputUnitForConstant = compiler.deferredLoadTask.outputUnitForConstant;
     var mainOutputUnit = compiler.deferredLoadTask.mainOutputUnit;
     var lib =
         compiler.libraryLoader.lookupLibrary(Uri.parse("memory:lib.dart"));
     var backend = compiler.backend;
-    List<Constant> allConstants = [];
+    List<ConstantValue> allConstants = [];
 
-    addConstantWithDependendencies(Constant c) {
+    addConstantWithDependendencies(ConstantValue c) {
       allConstants.add(c);
       c.getDependencies().forEach(addConstantWithDependendencies);
     }
 
     backend.constants.compiledConstants.forEach(addConstantWithDependendencies);
     for (String stringValue in ["cA", "cB", "cC"]) {
-      Constant constant = allConstants.firstWhere((constant) {
-        return constant is StringConstant
-            && constant.value.slowToString() == stringValue;
+      ConstantValue constant = allConstants.firstWhere((constant) {
+        return constant.isString
+            && constant.primitiveValue.slowToString() == stringValue;
       });
       Expect.notEquals(null, outputUnitForConstant(constant));
       Expect.notEquals(mainOutputUnit, outputUnitForConstant(constant));
     }
   }));
 }
 
 // The main library imports lib1 and lib2 deferred and use lib1.foo1 and
 // lib2.foo2.  This should trigger seperate outputunits for main, lib1 and lib2.
 //
@@ skipping 11 matching lines @@
   print(lib.L);
 }
 """, "lib.dart": """
 class C {
   final a;
   const C(this.a);
 }
 
 const L = const {"cA": const C(const {"cB": "cC"})};
 """,};