Add a hash map for a raw object to id mapping, this table will be used during snapshot writing in o…

runtime/vm/weak_table.h

 // Copyright (c) 2013, 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_WEAK_TABLE_H_
 #define VM_WEAK_TABLE_H_
 
 #include "vm/globals.h"
 
 #include "platform/assert.h"
@@ skipping 74 matching lines @@
       if (obj == key) {
         return ValueAt(idx);
       }
       idx = (idx + 1) & mask;
       obj = ObjectAt(idx);
     }
     ASSERT(ValueAt(idx) == 0);
     return 0;
   }
 
+  void Reset();
+
  private:
   enum {
     kObjectOffset = 0,
     kValueOffset,
     kEntrySize,
   };
 
   static const intptr_t kDeletedEntry = 1;  // Equivalent to a tagged NULL.
   static const intptr_t kMinSize = 8;
 
@@ skipping 58 matching lines @@
   intptr_t size_;
   intptr_t used_;
   intptr_t count_;
 
   DISALLOW_COPY_AND_ASSIGN(WeakTable);
 };
 
 }  // namespace dart
 
 #endif  // VM_WEAK_TABLE_H_