Support [handles] in validation test input format and add handle-related tests.

mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module mojo.test {
 
 struct StructA {
   uint64 i;
 };
 
 struct StructB {
   StructA struct_a;
 };
 
 struct StructC {
   uint8[] array;
 };
 
+struct StructD {
+  handle<message_pipe>[] message_pipes;
+};
+
+struct StructE {
+  StructD struct_d;
+  handle<data_pipe_consumer> data_pipe_consumer;
+};
+
 interface ConformanceTestInterface {
   Method0(float param0);
   Method1(StructA param0);
   Method2(StructB param0, StructA param1);
   Method3(bool[] param0);
   Method4(StructC param0, uint8[] param1);
+  Method5(StructE param0, handle<data_pipe_producer> param1);
 };
 
 struct BasicStruct {
   int32 a;
 };
 
 [Client=IntegrationTestInterface2]
 interface IntegrationTestInterface1 {
   Method0(BasicStruct param0);
 };
 
 [Client=IntegrationTestInterface1]
 interface IntegrationTestInterface2 {
   Method0() => (uint8[] param0);
 };
 
 }