Reduces the number of movw/movt instructions generated in ProbeTable. It
improves code size for CompileCallMegamorphic by about 10%.

BUG=none
TEST=none

Review URL: http://codereview.chromium.org/4220004/show

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5744 ce2b1a6d-e550-0410-aec6-3dcde31c8c00