Fix detection of UBFX in case of Word32And with immediate.

TBR=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/438563002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22744 ce2b1a6d-e550-0410-aec6-3dcde31c8c00