RegExpParser: Fix Reset()ting to the end.

RegExpParser: Fix Reset()ting to the end.

The bug would occur when we try to Reset() to a position already at the end.

This happens e.g., when the regexp ends with \u. What used to happen in that
case: 1) Advance past \ and u (to the end) (which wouldn't increase next_pos_
enough) 2) Try to parse 4 hex digits 3) When that failed, Reset() to the
position which should've been at the end but wasn't.

To be able to properly Reset() to a position at the end, we need to allow
next_pos_ to move beyond the end (since position() is next_pos_ - 1).

Minimal repro case:

var r = /foo\u/
r.test("foou") // should be true, was false.

(Note that \u not followed by 4 hex didits should be interpreted as an identity
escape. It already worked unless \u was at the end of the regexp.)

BUG=v8:3756
LOG=NO

Committed: https://crrev.com/978f41a1da57132f97fbfd9b6592cc99689e18ed
Cr-Commit-Position: refs/heads/master@{#25838}

[marja, 2014-12-15 14:55:37]

marja@chromium.org changed reviewers:
+ arv@chromium.org

[marja, 2014-12-15 14:55:38]

arv, could you have a look at this CL? (This is a prerequisite for the ES6
unicode regexps...)

[mathias, 2014-12-15 14:58:18]

Drive-by non-owner LGTM.

[arv (Not doing code reviews), 2014-12-15 15:53:45]

LGTM

https://codereview.chromium.org/802313003/diff/1/test/mjsunit/regress/regress...
File test/mjsunit/regress/regress-3756.js (right):

https://codereview.chromium.org/802313003/diff/1/test/mjsunit/regress/regress...
test/mjsunit/regress/regress-3756.js:21: assertFalse(r2.test("first\\u")); //
This used to return true (which was a bug).
long line here and below

[marja, 2014-12-16 11:45:52]

thx for review!

https://codereview.chromium.org/802313003/diff/1/test/mjsunit/regress/regress...
File test/mjsunit/regress/regress-3756.js (right):

https://codereview.chromium.org/802313003/diff/1/test/mjsunit/regress/regress...
test/mjsunit/regress/regress-3756.js:21: assertFalse(r2.test("first\\u")); //
This used to return true (which was a bug).
On 2014/12/15 15:53:45, arv wrote:
> long line here and below

Done; I wonder why presubmit didn't whine!

[marja, 2014-12-16 11:46:39]

The CQ bit was checked by marja@chromium.org

[commit-bot: I haz the power, 2014-12-16 11:47:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/802313003/40001

[commit-bot: I haz the power, 2014-12-16 12:14:18]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2014-12-17 10:14:05]

Patchset 3 (id:??) landed as
https://crrev.com/978f41a1da57132f97fbfd9b6592cc99689e18ed
Cr-Commit-Position: refs/heads/master@{#25838}