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

runtime/vm/isolate.cc

-// 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.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
-
-#include "vm/assert.h"
+#include "platform/assert.h"
 #include "vm/bigint_store.h"
 #include "vm/code_index_table.h"
 #include "vm/compiler_stats.h"
 #include "vm/dart_api_state.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/debuginfo.h"
 #include "vm/heap.h"
 #include "vm/message_queue.h"
 #include "vm/object_store.h"
@@ skipping 350 matching lines @@
 }
 
 
 void Isolate::VisitWeakPersistentHandles(HandleVisitor* visitor) {
   if (api_state() != NULL) {
     api_state()->VisitWeakHandles(visitor);
   }
 }
 
 }  // namespace dart