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

runtime/vm/isolate_win.h

Index: runtime/vm/isolate_win.h
diff --git a/runtime/vm/isolate_win.h b/runtime/vm/isolate_win.h
index 2561746681f258b1725ac03d9e411bfe5e86974c..dd4d5c298a51ec7751cce80a1153e31a1a2ba4c7 100644
--- a/runtime/vm/isolate_win.h
+++ b/runtime/vm/isolate_win.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 isolate_win.h directly; use isolate.h instead.
 #endif
 
-#include "vm/assert.h"
+#include "platform/assert.h"
 #include "vm/globals.h"
 
 namespace dart {