Consistently make the bounds check for AccessArgumentsAt explicit.

Consistently make the bounds check for AccessArgumentsAt explicit.

This has the advantage that AccessArgumentsAt itself can't deopt anymore and the
bounds check is visible for the elimination phase. Furthermore, things are
simply more consistent now, a good thing in itself. :-)Committed: https://code.google.com/p/v8/source/detail?r=12721

[Michael Starzinger]

LGTM. As discussed offline, the benefits most certainly outweigh the additional
instructions for the GenerateArguments runtime call.

[Sven Panne]

As discussed offline, the "hot stuff" should be crankshafted, anyway, and this
should use less instructions. In addition, the Lithium instruction can't deopt
anymore, so this should be nicer to the register allocator.

What we would really need here is an optimization across Lithium operation
boundaries, so the cmp/branch/sub would be simplified to a sub/branch. Peephole
optimizations, anyone...?

Landing...