Fix Win64 compilation failure introduced by r10483.

src/deoptimizer.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 614 matching lines @@
   for (int i = 0; i < deferred_heap_numbers_.length(); i++) {
     HeapNumberMaterializationDescriptor d = deferred_heap_numbers_[i];
 
     // Check of the heap number to materialize actually belong to the frame
     // being extracted.
     Address slot = d.slot_address();
     if (parameters_top <= slot && slot < parameters_bottom) {
       Handle<Object> num = isolate_->factory()->NewNumber(d.value());
 
       int index = (info->parameters_count() - 1) -
-          (slot - parameters_top) / kPointerSize;
+          static_cast<int>(slot - parameters_top) / kPointerSize;
 
       if (FLAG_trace_deopt) {
         PrintF("Materializing a new heap number %p [%e] in slot %p"
                "for parameter slot #%d\n",
                reinterpret_cast<void*>(*num),
                d.value(),
                d.slot_address(),
                index);
       }
 
       info->SetParameter(index, *num);
     } else if (expressions_top <= slot && slot < expressions_bottom) {
       Handle<Object> num = isolate_->factory()->NewNumber(d.value());
 
       int index = info->expression_count() - 1 -
-          (slot - expressions_top) / kPointerSize;
+          static_cast<int>(slot - expressions_top) / kPointerSize;
 
       if (FLAG_trace_deopt) {
         PrintF("Materializing a new heap number %p [%e] in slot %p"
                "for expression slot #%d\n",
                reinterpret_cast<void*>(*num),
                d.value(),
                d.slot_address(),
                index);
       }
 
@@ skipping 965 matching lines @@
 
 void DeoptimizedFrameInfo::Iterate(ObjectVisitor* v) {
   v->VisitPointer(BitCast<Object**>(&function_));
   v->VisitPointers(parameters_, parameters_ + parameters_count_);
   v->VisitPointers(expression_stack_, expression_stack_ + expression_count_);
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal