Also handle elements in *RealNamed* api methods

Also handle elements in *RealNamed* api methods

Apparently the *RealNamed* API methods only have named variants, but were always used by the embedder to find elements as well. We'd never find them though, since we wouldn't even look
there.

This CL ensures we check whether the name is actually an array index.

I guess for all named API functions we should assume they are used similar to o["name"] where name could also be a number... At least we should make it uniform between embedder and V8. This matches us up with their expectations for now...

BUG=v8:4137
LOG=n

Committed: https://crrev.com/028025f07e26ee7f962ff0a1ab9362868e58bac9
Cr-Commit-Position: refs/heads/master@{#29008}

[Jakob Kummerow, 2015-06-13 10:25:55]

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

[Jakob Kummerow, 2015-06-13 10:25:56]

LGTM

[Jakob Kummerow, 2015-06-13 10:31:58]

Still LGTM

[Toon Verwaest, 2015-06-13 10:32:09]

The CQ bit was checked by verwaest@chromium.org

[commit-bot: I haz the power, 2015-06-13 10:32:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1177383004/20001

[commit-bot: I haz the power, 2015-06-13 11:16:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-13 11:16:19]

Patchset 2 (id:??) landed as
https://crrev.com/028025f07e26ee7f962ff0a1ab9362868e58bac9
Cr-Commit-Position: refs/heads/master@{#29008}