fix FunctionCallbackInfo ambiguity

- when compiling tools that embed v8 with g++ FunctionCallbackInfo is currently ambigous
- more info: https://github.com/joyent/node/issues/7337
- original patch is here: https://codereview.appspot.com/78770045/

TBR=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/201573012

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@20217 ce2b1a6d-e550-0410-aec6-3dcde31c8c00