Tighten the code for MacroAssembler::ThrowUncatchable.

Tighten the code for MacroAssembler::ThrowUncatchable.

Test at the bottom in the unwind loop.  Eliminate the possibility of a
useless move to the eax/rax/r0 register (currently impossible because
this function has two call sites).  Do not explicitly zero the context
because we've already saved 0 as the context in the handler.

R=fschneider@chromium.org
BUG=
TEST=

Committed: http://code.google.com/p/v8/source/detail?r=9909

[fschneider, 2011-11-08 10:55:07]

lgtm