Fix porting bug in r6929

Review URL: http://codereview.chromium.org/6579036

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6932 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/x64/full-codegen-x64.cc

@@ -1095,7 +1095,7 @@ MemOperand FullCodeGenerator::ContextSlotOperandCheckExtensions(
   // This function is used only for loads, not stores, so it's safe to
   // return an rsi-based operand (the write barrier cannot be allowed to
   // destroy the rsi register).
-  return ContextOperand(temp, slot->index());
+  return ContextOperand(context, slot->index());
 }