Implement rewrite logic for assigning a temporary scoped_refptr to T*.

tools/clang/rewrite_scoped_refptr/tests/temp-assigned-to-field-init-expected.cc

 // Copyright (c) 2013 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.
 
 #include "scoped_refptr.h"
 
 struct Foo {
   int dummy;
 };
 
-int TestsAScopedRefptr() {
-  scoped_refptr<Foo> foo(new Foo);
-  if (foo.get())
-    return 1;
-  return 0;
+// Similar to case 2, but with a field initializer.
+scoped_refptr<Foo> GetBuggyFoo() {
+  return new Foo;
 }
+
+class ABuggyCtor {
+  ABuggyCtor() : f_(GetBuggyFoo()) {}
+  scoped_refptr<Foo> f_;
+};