[Bindings] Set "undefined" instead of deleting a property

This CL is a workaround fix for a crash issue; to set "undefined"
instead of deleting properties.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
Review-Url: https://codereview.chromium.org/2812563002
Cr-Commit-Position: refs/heads/master@{#463227}
Committed: https://chromium.googlesource.com/chromium/src/+/55f74b058ef1379b6c4bb527cee68c077729ab51

[peria, 2017-04-10 07:53:14]

Description was changed from

==========
Workaround to avoid crash.

This CL sets "undefined" instead of deleting properties, to fix
a crashe issue.

The root cause is in V8 normalization (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

to

==========
This CL sets "undefined" instead of deleting properties, to fix
a crash issue.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

[peria, 2017-04-10 07:55:08]

Description was changed from

==========
This CL sets "undefined" instead of deleting properties, to fix
a crash issue.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

to

==========
This CL is to fix a crash issue; sets "undefined" instead of deleting
properties.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

[peria, 2017-04-10 07:55:45]

Description was changed from

==========
This CL is to fix a crash issue; sets "undefined" instead of deleting
properties.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

to

==========
This CL is a workaround fix for a crash issue; to set "undefined"
instead of deleting properties.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

[peria, 2017-04-10 07:59:50]

peria@chromium.org changed reviewers:
+ bashi@chromium.org, haraken@chromium.org, yukishiino@chromium.org

[peria, 2017-04-10 07:59:50]

PTL.

As the description says, this is a workaround to fix a P1 crash issue, and what
this CL does is same with the one we chatted in http://crrev.com/2774233007

[bashi, 2017-04-10 08:24:46]

(defer to yukishiino@ and haraken@)

[haraken, 2017-04-10 08:27:08]

LGTM

The behavior after this CL is the same as the behavior before you started
removing the hidden value, right?

[peria, 2017-04-10 08:32:59]

On 2017/04/10 08:27:08, haraken wrote:
> LGTM
> 
> The behavior after this CL is the same as the behavior before you started
> removing the hidden value, right?

Yes, it should be same with before landing http://crrev.com/2774233007
(Precisely, the key strings are different. e.g. "ReadyPromise" -->
"ScriptPromise##Ready")

[peria, 2017-04-10 08:34:38]

The CQ bit was checked by peria@chromium.org

[commit-bot: I haz the power, 2017-04-10 08:34:50]

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

[Yuki, 2017-04-10 09:08:44]

LGTM.

We may want to remove V8PrivateProperty::deleteProperty for now, or add a
comment about the bug.

[commit-bot: I haz the power, 2017-04-10 12:04:44]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1491813278751870, "parent_rev":
"5209c4a740829998e6f5d78f0771d1fac8d20689", "commit_rev":
"55f74b058ef1379b6c4bb527cee68c077729ab51"}

[commit-bot: I haz the power, 2017-04-10 12:05:40]

Description was changed from

==========
This CL is a workaround fix for a crash issue; to set "undefined"
instead of deleting properties.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804
==========

to

==========
This CL is a workaround fix for a crash issue; to set "undefined"
instead of deleting properties.

The root cause seems to be in V8 (http://crbug.com/v8/6227),
but Blink can avoid the crash with this workaround.
The workaround is not on spec, but it works for many cases and we
have used the behavior for a while.


BUG=709804

Review-Url: https://codereview.chromium.org/2812563002
Cr-Commit-Position: refs/heads/master@{#463227}
Committed:
https://chromium.googlesource.com/chromium/src/+/55f74b058ef1379b6c4bb527cee6...
==========

[commit-bot: I haz the power, 2017-04-10 12:05:42]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/55f74b058ef1379b6c4bb527cee6...