Fix issue 974.

Fix issue 974.

When entering a finally block in unoptimized code, we unconditionally
save the accumulator register in the stack in case it holds a return
value or an exception.  In the case of a break, continue, or falling
off the end of the try or catch block, this value is unpredictable and
not necessarily safe for GC.

Committed: http://code.google.com/p/v8/source/detail?r=6035

[Mads Ager (chromium), 2010-12-15 16:12:57]

LGTM