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

tests/compiler/dart2js/field_type_simple_inferer_test.dart

Index: tests/compiler/dart2js/field_type_simple_inferer_test.dart
diff --git a/tests/compiler/dart2js/field_type_simple_inferer_test.dart b/tests/compiler/dart2js/field_type_simple_inferer_test.dart
index 534a7edaf7efbc0e6c11388f1c8e9b0b9f29e890..ad287786a35f5080b320e5d8f1eac59be8b0ef80 100644
--- a/tests/compiler/dart2js/field_type_simple_inferer_test.dart
+++ b/tests/compiler/dart2js/field_type_simple_inferer_test.dart
@@ -483,8 +483,8 @@ void doTest(String test, bool disableInlining, Map<String, Function> fields) {
       name,
       disableInlining,
       (compiler, field) {
-        TypeMask type = f(compiler.typesTask);
-        var inferrer = compiler.typesTask.typesInferrer;
+        TypeMask type = f(compiler.commonMasks);
+        var inferrer = compiler.globalInference.typesInferrer;
         TypeMask inferredType =
             simplify(inferrer.getTypeOfElement(field), inferrer.compiler);
         Expect.equals(type, inferredType, test);