Do not compact weak fixed array when re-allocating new backing store.

Do not compact weak fixed array when re-allocating new backing store.

JSObject::UnregisterPrototypeUser relies on the index of the weak
fixed array entry not to change.

See commit 1e65e2018.

There is no bug currently, because we would only re-allocate if there is no empty slot left. In which case there is no actual compaction going on during re-allocation.

R=jkummerow@chromium.org, mvstanton@chromium.org

Committed: https://crrev.com/147299b9fdda49eaf29998bb0157bc01337425c3
Cr-Commit-Position: refs/heads/master@{#30251}

[mvstanton, 2015-08-19 13:52:12]

LGTM with the one nit.

https://codereview.chromium.org/1294883004/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1294883004/diff/1/src/objects.cc#newcode7868
src/objects.cc:7868: }
How about calling set_last_used_index(index); here.

[Yang, 2015-08-19 13:57:16]

On 2015/08/19 13:52:12, mvstanton wrote:
> LGTM with the one nit.
> 
> https://codereview.chromium.org/1294883004/diff/1/src/objects.cc
> File src/objects.cc (right):
> 
> https://codereview.chromium.org/1294883004/diff/1/src/objects.cc#newcode7868
> src/objects.cc:7868: }
> How about calling set_last_used_index(index); here.

We are going to call WeakFixedArray::Set right after Allocate anyways, which
calls set_last_use_index.

[Yang, 2015-08-19 13:58:04]

The CQ bit was checked by yangguo@chromium.org

[commit-bot: I haz the power, 2015-08-19 13:58:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1294883004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1294883004/1

[commit-bot: I haz the power, 2015-08-19 14:29:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-19 14:29:58]

Patchset 1 (id:??) landed as
https://crrev.com/147299b9fdda49eaf29998bb0157bc01337425c3
Cr-Commit-Position: refs/heads/master@{#30251}