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

tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart

Index: tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart b/tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart
index c12eff30fc8c1a1a8e3b65163ea9ce0b8a557eda..4ea68a94f7e2c68c0943b8dae178e4b4881f2839 100644
--- a/tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_const_closure2_test.dart
@@ -29,7 +29,7 @@ void main() {
   Uri uri = new Uri(scheme: 'source');
   var compiler = compilerFor(TEST, uri);
   asyncTest(() => compiler.run(uri).then((_) {
-    var typesInferrer = compiler.typesTask.typesInferrer;
+    var typesInferrer = compiler.globalInference.typesInferrer;
 
     checkReturn(String name, type) {
       var element = findElement(compiler, name);
@@ -38,7 +38,7 @@ void main() {
           name);
     }
 
-    checkReturn('method', compiler.typesTask.numType);
-    checkReturn('returnNum', compiler.typesTask.numType);
+    checkReturn('method', compiler.commonMasks.numType);
+    checkReturn('returnNum', compiler.commonMasks.numType);
   }));
 }