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.

Review URL: http://codereview.chromium.org/5883003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6035 ce2b1a6d-e550-0410-aec6-3dcde31c8c00