Rewind additional parser state when reinterpreting arrow arguments

Rewind additional parser state when reinterpreting arrow arguments

The new ParserCheckpoint mechanism resets some state, notably the
bailout ID counter but also some statement counters (only applicable
once we get "do" expressions) when we decide to reinterpret a comma
expression as arrow function arguments.

R=marja@chromium.org, rossberg@chromium.org
BUG=v8:3475
LOG=N

Committed: https://code.google.com/p/v8/source/detail?r=22906

[wingo, 2014-08-05 13:10:09]

Perhaps there is a way to do this in a less nasty fashion, dunno.  Hold your
nose and PTAL :)

[rossberg, 2014-08-05 13:51:31]

Yeah, the problem I see here is that this probably won't work anymore once we
introduce default parameters. But I guess it's okay as a temporary solution.

https://codereview.chromium.org/437393004/diff/1/src/preparser.h
File src/preparser.h (right):

https://codereview.chromium.org/437393004/diff/1/src/preparser.h#newcode2052
src/preparser.h:2052: checkpoint.Save(this);
Why the separate Save method instead of just

  ParserCheckpoint checkpoint(this);

[wingo, 2014-08-05 14:18:26]

Updated patchset to give ParserCheckpoint an argument.  The patch is rebased, so
the interdiffs aren't as useful as they could be.  Sorry about that.

[rossberg, 2014-08-05 14:52:46]

lgtm

[marja, 2014-08-05 16:46:01]

omg, lgtm. thx for fixing!

[wingo, 2014-08-06 09:07:05]

Committed patchset #2 manually as 22906 (presubmit successful).