Store constant variable initializers in elements.

pkg/compiler/lib/src/js_backend/constant_handler_javascript.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.
 
 part of js_backend;
 
 /// [ConstantCompilerTask] for compilation of constants for the JavaScript
 /// backend.
 ///
 /// Since this task needs to distinguish between frontend and backend constants
@@ skipping 18 matching lines @@
   ConstantValue getConstantValue(ConstantExpression expression) {
     return dartConstantCompiler.getConstantValue(expression);
   }
 
   @override
   ConstantValue getConstantValueForVariable(VariableElement element) {
     return dartConstantCompiler.getConstantValueForVariable(element);
   }
 
   @override
-  ConstantExpression getConstantForVariable(VariableElement element) {
-    return dartConstantCompiler.getConstantForVariable(element);
-  }
-
-  @override
   ConstantExpression compileConstant(VariableElement element) {
     return measure(() {
       // TODO(het): Only report errors from one of the constant compilers
       ConstantExpression result = dartConstantCompiler.compileConstant(element);
       jsConstantCompiler.compileConstant(element);
       return result;
     });
   }
 
   @override
   void evaluate(ConstantExpression constant) {
     return measure(() {
       dartConstantCompiler.evaluate(constant);
       jsConstantCompiler.evaluate(constant);
     });
   }
 
-  void compileVariable(VariableElement element) {
-    measure(() {
-      jsConstantCompiler.compileVariable(element);
+  @override
+  ConstantExpression compileVariable(VariableElement element) {
+    return measure(() {
+      return jsConstantCompiler.compileVariable(element);
     });
   }
 
   ConstantExpression compileNode(Node node, TreeElements elements,
       {bool enforceConst: true}) {
     return measure(() {
       ConstantExpression result = dartConstantCompiler
           .compileNode(node, elements, enforceConst: enforceConst);
       jsConstantCompiler.compileNode(node, elements,
           enforceConst: enforceConst);
@@ skipping 210 matching lines @@
     // TODO(ahe): This doesn't belong here. Rename this class and generalize.
     var closureClassMap = constants
         .compiler.closureToClassMapper.closureMappingCache
         .remove(node);
     if (closureClassMap != null) {
       closureClassMap
           .removeMyselfFrom(constants.compiler.enqueuer.codegen.universe);
     }
   }
 }