Revert "Adjusts dart2js backend to handle method type arguments."

tests/language/generic_methods_new_test.dart

-// Copyright (c) 2016, 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.
-//
-// DartOptions=--generic-method-syntax
-
-/// Dart test on the usage of method type arguments in object creation. With
-/// '--generic-method-syntax', the type argument is available at runtime,
-/// but erased to `dynamic`.
-
-library generic_methods_new_test;
-
-import "package:expect/expect.dart";
-
-class C<E> {
-  E e;
-  C(this.e);
-}
-
-C<T> f1<T>(T t) => new C<T>(t);
-
-List<T> f2<T>(T t) => <T>[t];
-
-main() {
-  C c = f1<int>(42);
-  List i = f2<String>("Hello!");
-  Expect.isTrue(c is C<int> && c is C<String>); // C<dynamic>.
-  Expect.isTrue(i is List<String> && i is List<int>); // List<dynamic>.
-  Expect.equals(c.e, 42);
-  Expect.equals(i[0], "Hello!");
-}