Make CompilerTask independent of compiler.

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
 /// the actual compilation of the constants is forwarded to a
 /// [DartConstantCompiler] for the frontend interpretation of the constants and
 /// to a [JavaScriptConstantCompiler] for the backend interpretation.
 class JavaScriptConstantTask extends ConstantCompilerTask {
   DartConstantCompiler dartConstantCompiler;
   JavaScriptConstantCompiler jsConstantCompiler;
 
   JavaScriptConstantTask(Compiler compiler)
       : this.dartConstantCompiler = new DartConstantCompiler(compiler),
         this.jsConstantCompiler = new JavaScriptConstantCompiler(compiler),
-        super(compiler);
+        super(compiler.measurer);
 
   String get name => 'ConstantHandler';
 
   @override
   ConstantSystem get constantSystem => dartConstantCompiler.constantSystem;
 
   @override
   bool hasConstantValue(ConstantExpression expression) {
     return dartConstantCompiler.hasConstantValue(expression);
   }
@@ skipping 276 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);
     }
   }
 }