Merged r19535, r19549, r19584 into 3.24 branch.

Fix for a smi stores optimization on x64 with a regression test.

Fix for failing asserts in HBoundsCheck code generation on x64: index register should be zero extended.

Handle arguments objects in frame when materializing arguments

BUG=345715,345820,347262
LOG=N
R=danno@chromium.org

Review URL: https://codereview.chromium.org/180743009

git-svn-id: https://v8.googlecode.com/svn/branches/3.24@19611 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/3.24' into 3.24