Revert "Remove Registry from registerMetadataConstant" and "Serialize metadata"

pkg/compiler/lib/src/js_backend/namer.dart

 // Copyright (c) 2011, 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.
 
 part of js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  *
  * Names are generated through three stages:
@@ skipping 1654 matching lines @@
   void visitFunction(FunctionConstantValue constant, [_]) {
     add(constant.element.name);
   }
 
   @override
   void visitNull(NullConstantValue constant, [_]) {
     add('null');
   }
 
   @override
-  void visitNonConstant(NonConstantValue constant, [_]) {
-    add('null');
-  }
-
-  @override
   void visitInt(IntConstantValue constant, [_]) {
     // No `addRoot` since IntConstants are always inlined.
     if (constant.primitiveValue < 0) {
       add('m${-constant.primitiveValue}');
     } else {
       add('${constant.primitiveValue}');
     }
   }
 
   @override
@@ skipping 124 matching lines @@
       hash = _finish(constant.accept(this, null));
       hashes[constant] = hash;
     }
     return hash;
   }
 
   @override
   int visitNull(NullConstantValue constant, [_]) => 1;
 
   @override
-  int visitNonConstant(NonConstantValue constant, [_]) => 1;
-
-  @override
   int visitBool(BoolConstantValue constant, [_]) {
     return constant.isTrue ? 2 : 3;
   }
 
   @override
   int visitFunction(FunctionConstantValue constant, [_]) {
     return _hashString(1, constant.element.name);
   }
 
   @override
@@ skipping 217 matching lines @@
   void addSuggestion(String original, String suggestion) {
     assert(!_suggestedNames.containsKey(original));
     _suggestedNames[original] = suggestion;
   }
 
   bool hasSuggestion(String original) => _suggestedNames.containsKey(original);
   bool isSuggestion(String candidate) {
     return _suggestedNames.containsValue(candidate);
   }
 }