Fix legacy const for-of/in destructuring

Fix legacy const for-of/in destructuring

Previously, using legacy const in for-of/in loops led to a check-fail
in the parser. This was due to the fact that the destructuring bind
led to an undefined initialization to undefined in the parser, which
caused the for loop code to go down a strange path. This patch
eliminates the undefined initialization in variables declared in
for-in/of loops, so that that path is not used and the error is
fixed.

BUG=v8:4461
LOG=Y
R=adamk

Committed: https://crrev.com/38465598c82ac73ca4dcf3f2855df1ee1709a6d6
Cr-Commit-Position: refs/heads/master@{#31117}

[Dan Ehrenberg, 2015-10-05 18:05:59]

The CQ bit was checked by littledan@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-05 18:06:29]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1385913003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1385913003/1

[commit-bot: I haz the power, 2015-10-05 18:52:44]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-10-05 18:52:45]

Dry run: This issue passed the CQ dry run.

[adamk, 2015-10-05 20:13:19]

https://codereview.chromium.org/1385913003/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/1385913003/diff/1/src/parser.cc#newcode2556
src/parser.cc:2556: if (is_for_iteration_variable &&
parsing_result->descriptor.mode == CONST) {
Could you fix this here instead, by resetting needs_init to false for
CONST_LEGACY as well as CONST?

[Dan Ehrenberg, 2015-10-05 22:09:41]

On 2015/10/05 at 20:13:19, adamk wrote:
> https://codereview.chromium.org/1385913003/diff/1/src/parser.cc
> File src/parser.cc (right):
> 
> https://codereview.chromium.org/1385913003/diff/1/src/parser.cc#newcode2556
> src/parser.cc:2556: if (is_for_iteration_variable &&
parsing_result->descriptor.mode == CONST) {
> Could you fix this here instead, by resetting needs_init to false for
CONST_LEGACY as well as CONST?

Done, I just had to change another case where needs_init is checked later to get
at whether it's CONST_LEGACY.

[Dan Ehrenberg, 2015-10-05 22:09:47]

The CQ bit was checked by littledan@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-05 22:10:08]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1385913003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1385913003/20001

[adamk, 2015-10-05 22:17:51]

lgtm

https://codereview.chromium.org/1385913003/diff/20001/src/pattern-rewriter.cc
File src/pattern-rewriter.cc (right):

https://codereview.chromium.org/1385913003/diff/20001/src/pattern-rewriter.cc...
src/pattern-rewriter.cc:178: } else if (value != nullptr && (descriptor_->mode
== CONST_LEGACY ||
I like this better, too; the old code is very odd looking.

[commit-bot: I haz the power, 2015-10-05 22:31:38]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-10-05 22:31:38]

Dry run: This issue passed the CQ dry run.

[Dan Ehrenberg, 2015-10-05 22:34:34]

The CQ bit was checked by littledan@chromium.org

[commit-bot: I haz the power, 2015-10-05 22:34:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1385913003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1385913003/20001

[commit-bot: I haz the power, 2015-10-05 22:36:25]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-05 22:36:47]

Patchset 2 (id:??) landed as
https://crrev.com/38465598c82ac73ca4dcf3f2855df1ee1709a6d6
Cr-Commit-Position: refs/heads/master@{#31117}