Add dead CodeRegionTable for tracking overwritten Dart code

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 3322 matching lines @@
     return RoundedAllocationSize(sizeof(RawCode) + (len * kBytesPerElement));
   }
   static RawCode* FinalizeCode(const Function& function,
                                Assembler* assembler,
                                bool optimized = false);
   static RawCode* FinalizeCode(const char* name,
                                Assembler* assembler,
                                bool optimized = false);
   static RawCode* LookupCode(uword pc);
   static RawCode* LookupCodeInVmIsolate(uword pc);
+  static RawCode* FindCode(uword pc, int64_t timestamp);
 
   int32_t GetPointerOffsetAt(int index) const {
     return *PointerOffsetAddrAt(index);
   }
   intptr_t GetTokenIndexOfPC(uword pc) const;
 
   // Find pc, return 0 if not found.
   uword GetPatchCodePc() const;
   uword GetLazyDeoptPc() const;
 
@@ skipping 3380 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_