[proxies] Fix HasProperty and getOwnPropertySymbols

[proxies] Fix HasProperty and getOwnPropertySymbols

JSProxy::HasProperty was missing an early "return Nothing<bool>".
KeyAccumulator's FilterProxyKeys() didn't handle SKIP_STRINGS correctly.

BUG=v8:1543
LOG=n
R=cbruni@chromium.org

Committed: https://crrev.com/453e1dfa7abb7ab1061db3af8694a1e32d11aa71
Cr-Commit-Position: refs/heads/master@{#32699}

[Jakob Kummerow, 2015-12-08 13:33:58]

Found these by running test262. PTAL.

[Camillo Bruni, 2015-12-08 13:44:07]

lgtm

[Jakob Kummerow, 2015-12-09 09:11:54]

The CQ bit was checked by jkummerow@chromium.org

[commit-bot: I haz the power, 2015-12-09 09:12:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1505253002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1505253002/1

[commit-bot: I haz the power, 2015-12-09 09:40:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-12-09 09:41:17]

Description was changed from

==========
[proxies] Fix HasProperty and getOwnPropertySymbols

JSProxy::HasProperty was missing an early "return Nothing<bool>".
KeyAccumulator's FilterProxyKeys() didn't handle SKIP_STRINGS correctly.

BUG=v8:1543
LOG=n
R=cbruni@chromium.org
==========

to

==========
[proxies] Fix HasProperty and getOwnPropertySymbols

JSProxy::HasProperty was missing an early "return Nothing<bool>".
KeyAccumulator's FilterProxyKeys() didn't handle SKIP_STRINGS correctly.

BUG=v8:1543
LOG=n
R=cbruni@chromium.org

Committed: https://crrev.com/453e1dfa7abb7ab1061db3af8694a1e32d11aa71
Cr-Commit-Position: refs/heads/master@{#32699}
==========

[commit-bot: I haz the power, 2015-12-09 09:41:18]

Patchset 1 (id:??) landed as
https://crrev.com/453e1dfa7abb7ab1061db3af8694a1e32d11aa71
Cr-Commit-Position: refs/heads/master@{#32699}