Begin writing tests of the runtime checks needed for Dart 2.0 soundness.

pkg/front_end/testcases/runtime_checks/contravariant_generic_method_type_parameter.dart.direct.expect

+library test;
+import self as self;
+import "dart:core" as core;
+
+typedef F<T extends core::Object> = (T) → void;
+class C<T extends core::Object> extends core::Object {
+  default constructor •() → void
+    : super core::Object::•()
+    ;
+  method f<U extends (self::C::T) → void>(self::C::f::U x) → void {}
+}
+static method g(self::C<core::num> c) → void {
+  c.f<(core::Object) → void>((core::Object o) → dynamic {});
+}
+static method test() → void {
+  self::g(new self::C::•<core::int>());
+}
+static method main() → void {}