[turbofan] Eliminate redundant masking operations for word8/word16 stores.

There's no need to apply 0xff when storing 8-bit values or 0xffff when
storing 16-bit values.

TEST=unittests
R=titzer@chromium.org

Review URL: https://codereview.chromium.org/642033002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24492 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Move js perf test to another directory.

TBR=dslomov@chromium.org, bmeurer@chromium.org

Review URL: https://codereview.chromium.org/641033003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24493 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
[ia32] Use more efficient encoding when loading integer constants.

R=titzer@chromium.org

Review URL: https://codereview.chromium.org/642053002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24494 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Convert `obj` ToObject in Object.keys()

BUG=v8:3587
LOG=Y
R=arv@chromium.org, dslomov@chromium.org

Review URL: https://codereview.chromium.org/585373003

Patch from Caitlin Potter <caitpotter88@gmail.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24495 ce2b1a6d-e550-0410-aec6-3dcde31c8c00