ARM: Replace branch with conditional store in function prologue.

ARM: Replace branch with conditional store in function prologue.

Use conditional store to replace the receiver with undefined for
strict mode functions and builtins instead of branching code. This
has similar performance characteristics but saves one branch
instruction per strict mode function.

R=svenpanne@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=17412

[Benedikt Meurer, 2013-10-28 10:17:14]

Hey Sven,
This is a trivial optimization.
PTAL
-- Benedikt

[Sven Panne, 2013-10-28 10:28:41]

lgtm

[Benedikt Meurer, 2013-10-28 10:30:04]

Committed patchset #1 manually as r17412.