Move compile-time constant registrations to the backend.

tests/compiler/dart2js/mirrors_used_test.dart

 // Copyright (c) 2013, 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 the @MirrorsUsed annotation suppress hints and that only
 /// requested elements are retained for reflection.
 library dart2js.test.mirrors_used_test;
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
@@ skipping 74 matching lines @@
                 compiler.backend.isNeededForReflection(classMember),
                 '$classMember');
           });
         } else {
           Expect.isFalse(
               compiler.backend.isNeededForReflection(member), '$member');
         }
       });
     }
 
-    // There should at least be three metadata constants:
-    // 1. The type literal 'Foo'.
-    // 2. The list 'const [Foo]'.
-    // 3. The constructed constant for 'MirrorsUsed'.
-    Expect.isTrue(compiler.metadataHandler.compiledConstants.length >= 3);
+    // There should at least be one metadata constant:
+    // 1. The constructed constant for 'MirrorsUsed'.
+    Expect.isTrue(compiler.backend.metadataConstants.length >= 1);
 
     // Make sure that most of the metadata constants aren't included in the
     // generated code.
-    for (Constant constant in compiler.metadataHandler.compiledConstants) {
-      if (constant is TypeConstant && '${constant.representedType}' == 'Foo') {
-        // The type literal 'Foo' is retained as a constant because it is being
-        // passed to reflectClass.
-        continue;
-      }
+    for (var dependency in compiler.backend.metadataConstants) {
+      Constant constant = dependency.constant;
       Expect.isFalse(
           compiler.constantHandler.compiledConstants.contains(constant),
           '$constant');
     }
 
     // The type literal 'Foo' is both used as metadata, and as a plain value in
     // the program. Make sure that it isn't duplicated.
     int fooConstantCount = 0;
-    for (Constant constant in compiler.metadataHandler.compiledConstants) {
+    for (Constant constant in compiler.constantHandler.compiledConstants) {
       if (constant is TypeConstant && '${constant.representedType}' == 'Foo') {
         fooConstantCount++;
       }
     }
     Expect.equals(
         1, fooConstantCount,
         "The type literal 'Foo' is duplicated or missing.");
   }));
 }
 
@@ skipping 21 matching lines @@
 library lib;
 
 import 'dart:mirrors';
 
 useReflect(type) {
   print(new Symbol('Foo'));
   print(MirrorSystem.getName(reflectClass(type).owner.qualifiedName));
 }
 """,
 };