Fix corner-case behavior of JSObject::SetPrototype.

Fix corner-case behavior of JSObject::SetPrototype.

Setting the prototype to whatever it currently is must succeed even if
the object is not extensible.

R=verwaest@chromium.org
BUG=

Committed: https://crrev.com/193410062ec8a0722dd261f9d14bf1ec29d54f7b
Cr-Commit-Position: refs/heads/master@{#31527}

[Toon Verwaest, 2015-10-22 13:21:07]

lgtm with nit

https://codereview.chromium.org/1423603002/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1423603002/diff/1/src/objects.cc#newcode13952
src/objects.cc:13952: real_receiver =
PrototypeIterator::GetCurrent<JSObject>(iter);
This code is a bit overkill, since this is only relevant for JSGlobalObjects
behind JSGlobalProxies, but I guess it's ok for now.
Real receiver is quite a bad name though...

https://codereview.chromium.org/1423603002/diff/1/src/objects.cc#newcode13957
src/objects.cc:13957: Handle<Map> map(real_receiver->map());
Slight overkill to allocate a handle to just dereference it once below...

[neis, 2015-10-23 14:26:41]

The CQ bit was checked by neis@chromium.org

[commit-bot: I haz the power, 2015-10-23 14:26:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1423603002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1423603002/1

[neis, 2015-10-23 14:26:54]

https://codereview.chromium.org/1423603002/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/1423603002/diff/1/src/objects.cc#newcode13957
src/objects.cc:13957: Handle<Map> map(real_receiver->map());
On 2015/10/22 13:21:07, Toon Verwaest wrote:
> Slight overkill to allocate a handle to just dereference it once below...

It's used again further down.

[commit-bot: I haz the power, 2015-10-23 14:52:16]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-23 14:52:35]

Patchset 1 (id:??) landed as
https://crrev.com/193410062ec8a0722dd261f9d14bf1ec29d54f7b
Cr-Commit-Position: refs/heads/master@{#31527}