[x64] 64-bit shift left by 32 or more covers sign/zero extend.

TEST=unittests
R=jarin@chromium.org

Review URL: https://codereview.chromium.org/704703002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25123 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
X87:  [turbofan] Add AllocateHeapNumberStub to avoid runtime call.

port ee95552f291d3c1fff78bc4f8d8621e84976e5c9 (r25107)

original commit message:
  [turbofan] Add AllocateHeapNumberStub to avoid runtime call.

BUG=
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/701033002

Patch from Chunyang Dai <chunyang.dai@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25124 ce2b1a6d-e550-0410-aec6-3dcde31c8c00