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

tests/compiler/dart2js/simple_inferrer_final_field_test.dart

Index: tests/compiler/dart2js/simple_inferrer_final_field_test.dart
diff --git a/tests/compiler/dart2js/simple_inferrer_final_field_test.dart b/tests/compiler/dart2js/simple_inferrer_final_field_test.dart
index 1b74240368061c619c5d168c61b2cbe90b8c88c6..a3a25166c37e329490bc538eaaa859e3d3bdb87a 100644
--- a/tests/compiler/dart2js/simple_inferrer_final_field_test.dart
+++ b/tests/compiler/dart2js/simple_inferrer_final_field_test.dart
@@ -31,7 +31,7 @@ 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;
 
     checkFieldTypeInClass(String className, String fieldName, type) {
       var cls = findElement(compiler, className);
@@ -40,11 +40,11 @@ void main() {
           simplify(typesInferrer.getTypeOfElement(element), compiler));
     }
 
-    checkFieldTypeInClass('A', 'intField', compiler.typesTask.uint31Type);
+    checkFieldTypeInClass('A', 'intField', compiler.commonMasks.uint31Type);
     checkFieldTypeInClass('A', 'giveUpField1',
         findTypeMask(compiler, 'Interceptor', 'nonNullSubclass'));
     checkFieldTypeInClass('A', 'giveUpField2',
-        compiler.typesTask.dynamicType.nonNullable());
-    checkFieldTypeInClass('A', 'fieldParameter', compiler.typesTask.uint31Type);
+        compiler.commonMasks.dynamicType.nonNullable());
+    checkFieldTypeInClass('A', 'fieldParameter', compiler.commonMasks.uint31Type);
   }));
 }