Fix toString() behavior on proxy objects.

Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel

Committed: https://crrev.com/7e4c4cb5c5492bb1cbf408cba1699eee4e92cb24
Cr-Commit-Position: refs/heads/master@{#37289}

[Franzi, 2016-06-27 06:43:58]

Description was changed from

==========
Fix toString() behavior on proxies.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() is discarded if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=
==========

to

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=
==========

[Franzi, 2016-06-27 06:44:38]

franzih@chromium.org changed reviewers:
+ adamk@chromium.org, verwaest@chromium.org

[Franzi, 2016-06-27 06:49:44]

Description was changed from

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=
==========

to

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
==========

[Franzi, 2016-06-27 10:46:17]

Hi, 

I changed the behavior of toString() for proxy objects. Now we're using the same
order as the specification. Please have a look. 

Thanks, 

Franzi

[Toon Verwaest, 2016-06-27 10:50:40]

lgtm

[Franzi, 2016-06-27 10:56:57]

The CQ bit was checked by franzih@chromium.org

[commit-bot: I haz the power, 2016-06-27 10:57:06]

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

[commit-bot: I haz the power, 2016-06-27 12:11:40]

Description was changed from

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
==========

to

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
==========

[commit-bot: I haz the power, 2016-06-27 12:11:40]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-27 12:12:56]

Description was changed from

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
==========

to

==========
Fix toString() behavior on proxy objects.

Proxy objects need special treatment in toString(). Usually, we use the
@@toStringTag, if it is set, otherwise we determine the result of toString()
by checking IsArray() and other internal slots. According to
ES2017 19.1.3.6, IsArray() and the internal slots  must be checked first,
then get(@@toStringTag). The result of IsArray() and internal slots is discarded
if
@@toStringTag is set. For proxy
objects, we must obey this order, because get() can have side-effects, i.e.,
revoke the proxy. For all other objects, we can skip the check of the
internal slots, if @@toStringTag is set.

BUG=

CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel

Committed: https://crrev.com/7e4c4cb5c5492bb1cbf408cba1699eee4e92cb24
Cr-Commit-Position: refs/heads/master@{#37289}
==========

[commit-bot: I haz the power, 2016-06-27 12:12:57]

Patchset 2 (id:??) landed as
https://crrev.com/7e4c4cb5c5492bb1cbf408cba1699eee4e92cb24
Cr-Commit-Position: refs/heads/master@{#37289}