Move assert.h/assert.cc from runtime/vm to runtime/platform

runtime/vm/assembler_arm.h

Index: runtime/vm/assembler_arm.h
diff --git a/runtime/vm/assembler_arm.h b/runtime/vm/assembler_arm.h
index 28a1463e524a99db11ef9d7405b872693c1e77b3..edbaeb3b6fde26e0d8eb0e69c19a59d08edc1da3 100644
--- a/runtime/vm/assembler_arm.h
+++ b/runtime/vm/assembler_arm.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2012, 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.
 
@@ -9,7 +9,7 @@
 #error Do not include assembler_arm.h directly; use assembler.h instead.
 #endif
 
-#include "vm/assert.h"
+#include "platform/assert.h"
 #include "vm/constants_arm.h"
 
 namespace dart {