Stop sending Object.observe notifications for API accessor properties

Stop sending Object.observe notifications for API accessor properties

Such properties never notified prior to r21558, but the combination of
that change and r23163 led to sending notifications when they were
set via Object.defineProperty (but not when set via other means).

This also allows some cleanup in v8natives.js and objects.cc,
both of which were doing unnecessary contortions to produce the right
change records.

BUG=v8:3745
LOG=n

[adamk, 2014-12-10 23:33:45]

adamk@chromium.org changed reviewers:
+ jkummerow@chromium.org

[adamk, 2014-12-10 23:33:46]

Sending to jkummerow since he reviewed r23163, but not sure who the best
reviewer for this bit of code is.

[Jakob Kummerow, 2014-12-11 11:41:40]

Doing less work always LGTM :-)

However, I'm unsure about the cleanup in v8natives.js. Unless you're absolutely
certain that you're not cleaning up too much there, you should get a second
opinion on that.

https://codereview.chromium.org/791243002/diff/1/src/v8natives.js
File src/v8natives.js (left):

https://codereview.chromium.org/791243002/diff/1/src/v8natives.js#oldcode847
src/v8natives.js:847: // Step 3 - Special handling for length property.
Some of this code was ~3 years old and seems unrelated to Object.observe, e.g.
as modified by https://codereview.chromium.org/8890015. Are you sure we don't
need it any more?

[Jakob Kummerow, 2014-12-11 11:44:04]

On second thought, the trybot failures for test262 15.2.3.{6,7}-* seem to
indicate quite clearly that you *are* cleaning up too much.

[adamk, 2014-12-11 16:47:27]

Hooray for trybots, will slim down the cleanup.

https://codereview.chromium.org/791243002/diff/1/src/v8natives.js
File src/v8natives.js (left):

https://codereview.chromium.org/791243002/diff/1/src/v8natives.js#oldcode847
src/v8natives.js:847: // Step 3 - Special handling for length property.
On 2014/12/11 11:41:40, Jakob wrote:
> Some of this code was ~3 years old and seems unrelated to Object.observe, e.g.
> as modified by https://codereview.chromium.org/8890015. Are you sure we don't
> need it any more?

Arg, you're right, test262 not being in make check gets me half the time.

[adamk, 2014-12-11 20:26:07]

https://codereview.chromium.org/791243002/diff/20001/src/v8natives.js
File src/v8natives.js (left):

https://codereview.chromium.org/791243002/diff/20001/src/v8natives.js#oldcode893
src/v8natives.js:893: // respective TODO in Runtime_DefineDataPropertyUnchecked.
This TODO was taken care of by r21558, so at least we can remove this weird "set
the length twice" hack.

[Jakob Kummerow, 2014-12-12 09:29:52]

lgtm

[adamk, 2014-12-12 17:47:31]

The CQ bit was checked by adamk@chromium.org

[commit-bot: I haz the power, 2014-12-12 17:48:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/791243002/20001

[commit-bot: I haz the power, 2014-12-12 18:15:49]

Committed patchset #2 (id:20001)