Optimistically untag the input in tagged-to-i.

Also drop redundant jmp instruction in deferred code.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/182723003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19698 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Use fast path for sliced and external strings in ConvertCase.

R=dcarney@chromium.org
BUG=v8:3180
LOG=N

Review URL: https://codereview.chromium.org/180063002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19699 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
ia32: Simplify inlined Smi code for SAR.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/188483002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19700 ce2b1a6d-e550-0410-aec6-3dcde31c8c00