Rename Constant to ConstantValue and ConstExp to ConstantExpression.

sdk/lib/_internal/compiler/implementation/use_unused_api.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.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
@@ skipping 46 matching lines @@
   useIr(null, null, null);
   useCompiler(null);
   useTypes();
   useCodeEmitterTask(null);
 }
 
 useApi() {
   api.ReadStringFromUri uri;
 }
 
-void useConstant(constants.Constant constant, dart2jslib.ConstantSystem cs) {
+void useConstant(constants.ConstantValue constant,
+                 dart2jslib.ConstantSystem cs) {
   constant.isObject;
   cs.isBool(constant);
 }
 
 void useNode(tree.Node node) {
   node
     ..asBreakStatement()
     ..asCascade()
     ..asCatchBlock()
     ..asClassNode()
@@ skipping 164 matching lines @@
   compiler.forgetElement(null);
 }
 
 useTypes() {
   new dart_types.ResolvedTypedefType(null, null, null).unalias(null);
 }
 
 useCodeEmitterTask(js_emitter.CodeEmitterTask codeEmitterTask) {
   codeEmitterTask.oldEmitter.clearCspPrecompiledNodes();
 }