Zhang Kun.  For now we only emit movw and movt in places where no
relocation is needed.  Small performance boost (around 0.5%).
Also adds support for turning ALU operations (eor etc.) with
large immediates into mvn or movw followed by a register-based
ALU operation.
Review URL: http://codereview.chromium.org/2821014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@4913 ce2b1a6d-e550-0410-aec6-3dcde31c8c00