[regexp] Fix writing of lastIndex in JSRegExp::Initialize.

[regexp] Fix writing of lastIndex in JSRegExp::Initialize.

The lastIndex property must be written with the semantics of a strict [[Set]],
so an exception must be thrown when the attributes don't allow writing.  We used
to ignore the attributes.

R=littledan@chromium.org, yangguo@chromium.org
BUG=v8:5138
Committed: https://crrev.com/40641fbc031857d574550cc608c5f51893d9593d
Cr-Commit-Position: refs/heads/master@{#37369}

[neis, 2016-06-28 10:58:59]

PTAL.
There's an older regression test (the file that I deleted in my patchset),
originating from https://codereview.chromium.org/182003004/, that I'm unsure
about. The test is testing the wrong behavior. And I don't know how to update it
because I don't understand the connection between the test and the code change
it came with.

[Yang, 2016-06-28 11:19:06]

On 2016/06/28 10:58:59, neis wrote:
> PTAL.
> There's an older regression test (the file that I deleted in my patchset),
> originating from https://codereview.chromium.org/182003004/, that I'm unsure
> about. The test is testing the wrong behavior. And I don't know how to update
it
> because I don't understand the connection between the test and the code change
> it came with.

lgtm. The regression test was testing that allocation inside initialize does not
cause assertion. We can remove it now that a lot of the code paths changed
anyways.

[Dan Ehrenberg, 2016-06-28 18:55:00]

lgtm

[neis, 2016-06-29 08:18:11]

The CQ bit was checked by neis@chromium.org

[commit-bot: I haz the power, 2016-06-29 08:18:21]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-06-29 08:44:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-06-29 08:48:13]

Description was changed from

==========
[regexp] Fix writing of lastIndex in JSRegExp::Initialize.

The lastIndex property must be written with the semantics of a strict [[Set]],
so an exception must be thrown when the attributes don't allow writing.  We used
to ignore the attributes.

R=littledan@chromium.org, yangguo@chromium.org
BUG=v8:5138
==========

to

==========
[regexp] Fix writing of lastIndex in JSRegExp::Initialize.

The lastIndex property must be written with the semantics of a strict [[Set]],
so an exception must be thrown when the attributes don't allow writing.  We used
to ignore the attributes.

R=littledan@chromium.org, yangguo@chromium.org
BUG=v8:5138

Committed: https://crrev.com/40641fbc031857d574550cc608c5f51893d9593d
Cr-Commit-Position: refs/heads/master@{#37369}
==========

[commit-bot: I haz the power, 2016-06-29 08:48:14]

Patchset 1 (id:??) landed as
https://crrev.com/40641fbc031857d574550cc608c5f51893d9593d
Cr-Commit-Position: refs/heads/master@{#37369}