Rename the global inference task and reduce it's API surface by introducing the

tests/compiler/dart2js/map_tracer_keys_test.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.
 
 import 'package:expect/expect.dart';
 import "package:async_helper/async_helper.dart";
 import 'package:compiler/src/types/types.dart'
     show ContainerTypeMask, TypeMask;
 
 import 'compiler_helper.dart';
@@ skipping 37 matching lines @@
   doTest(key: "aList", bail: true, initial: true);
   doTest(value: "aList", initial: true);
 }
 
 void doTest({String key: "'d'", String value: "5.5", bool bail: false,
              bool initial: false}) {
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(generateTest(key, value, initial), uri,
       expectedErrors: 0, expectedWarnings: 0);
   asyncTest(() => compiler.run(uri).then((_) {
-    var typesTask = compiler.typesTask;
-    var typesInferrer = typesTask.typesInferrer;
+    var commonMasks = compiler.commonMasks;
+    var typesInferrer = compiler.globalInference.typesInferrer;
     var aDoubleType =
         typesInferrer.getTypeOfElement(findElement(compiler, 'aDouble'));
     var aListType =
         typesInferrer.getTypeOfElement(findElement(compiler, 'aList'));
 
-    Expect.equals(aDoubleType, typesTask.doubleType);
+    Expect.equals(aDoubleType, commonMasks.doubleType);
     Expect.isTrue(aListType is ContainerTypeMask);
     ContainerTypeMask container = aListType;
     TypeMask elementType = container.elementType;
     if (bail) {
-      Expect.equals(elementType, typesTask.dynamicType);
+      Expect.equals(elementType, commonMasks.dynamicType);
     } else {
-      Expect.equals(elementType, typesTask.uint31Type);
+      Expect.equals(elementType, commonMasks.uint31Type);
     }
   }));
 }