Decouple WorkItem from Compiler

tests/compiler/dart2js/patch_test.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.
 
 import 'dart:async';
 import 'package:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
 import 'package:compiler/src/compiler.dart';
 import 'package:compiler/src/diagnostics/messages.dart' show MessageKind;
 import 'package:compiler/src/elements/elements.dart';
@@ skipping 182 matching lines @@
           expectIsPatched: expectIsPatched, checkHasBody: true);
       if (expectIsPatched) {
         AstElement patch = ensure(
             compiler, "test", compiler.commonElements.coreLibrary.patch.find,
             expectIsPatch: true, checkHasBody: true);
         Expect.equals(origin.patch, patch);
         Expect.equals(patch.origin, origin);
         Expect.equals(patchText, patch.node.toString());
       }
 
-      compiler.analyzeElement(origin);
+      compiler.resolution.computeWorldImpact(origin);
       compiler.enqueuer.resolution.emptyDeferredQueueForTesting();
 
       DiagnosticCollector collector = compiler.diagnosticCollector;
       Expect.isTrue(collector.warnings.isEmpty,
           "Unexpected warnings: ${collector.warnings}");
       if (expectedError != null) {
         Expect.equals(expectedError, collector.errors.first.message.toString());
       } else {
         Expect.isTrue(
             collector.errors.isEmpty, "Unexpected errors: ${collector.errors}");
@@ skipping 902 matching lines @@
     await testPatchNonFunction();
 
     await testPatchAndSelector();
 
     await testEffectiveTarget();
 
     await testAnalyzeAllInjectedMembers();
     await testTypecheckPatchedMembers();
   });
 }