Some ARM architectures load 32-bit immediate constants more efficiently using movw/movt pairs rather than constant pool loads. This patch allows the assembler to generate one or the other load form at runtime depending on what is faster.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/11037023

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12755 ce2b1a6d-e550-0410-aec6-3dcde31c8c00