Fix build and test failures from packed array optimizations.

src/x64/macro-assembler-x64.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 4041 matching lines @@
     Register scratch,
     Label* no_map_match) {
   // Load the global or builtins object from the current context.
   movq(scratch, Operand(rsi, Context::SlotOffset(Context::GLOBAL_INDEX)));
   movq(scratch, FieldOperand(scratch, GlobalObject::kGlobalContextOffset));
 
   // Check that the function's map is the same as the expected cached map.
   movq(scratch, Operand(scratch,
                         Context::SlotOffset(Context::JS_ARRAY_MAPS_INDEX)));
 
-  size_t offset = expected_kind * kPointerSize +
+  int offset = expected_kind * kPointerSize +
       FixedArrayBase::kHeaderSize;
   cmpq(map_in_out, FieldOperand(scratch, offset));
   j(not_equal, no_map_match);
 
   // Use the transitioned cached map.
   offset = transitioned_kind * kPointerSize +
       FixedArrayBase::kHeaderSize;
   movq(map_in_out, FieldOperand(scratch, offset));
 }
 
@@ skipping 373 matching lines @@
   bind(&check_prototype);
   movq(rcx, FieldOperand(rbx, Map::kPrototypeOffset));
   cmpq(rcx, null_value);
   j(not_equal, &next);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64