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

runtime/vm/disassembler_arm.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/disassembler.h"
+
+#include "platform/assert.h"
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM.
 #if defined(TARGET_ARCH_ARM)
 
-#include "vm/disassembler.h"
-
-#include "vm/assert.h"
 
 namespace dart {
 
 int Disassembler::DecodeInstruction(char* hex_buffer, intptr_t hex_size,
                                     char* human_buffer, intptr_t human_size,
                                     uword pc) {
   UNIMPLEMENTED();
   return 0;
 }
 
 
 void Disassembler::Disassemble(uword start,
                                uword end,
                                DisassemblyFormatter* formatter) {
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM