[runtime] Remove useless DELETE builtin.

[runtime] Remove useless DELETE builtin.

The DELETE builtin calls through to %DeleteProperty anyway, so we
can as well skip the builtin completely and always call into the
runtime directly.  Also add different entries depending on whether
calling code is in sloppy or strict/strong mode.

R=yangguo@chromium.org

Committed: https://crrev.com/3d01d31fa94f7cda711c12735cb69a1fe795cc8d
Cr-Commit-Position: refs/heads/master@{#30148}

[Benedikt Meurer, 2015-08-13 08:52:58]

Hey Yang,

Moar cleanup to the builtins.
Please take a look.

Thanks,
Benedikt

[Yang, 2015-08-13 09:23:51]

On 2015/08/13 08:52:58, Benedikt Meurer wrote:
> Hey Yang,
> 
> Moar cleanup to the builtins.
> Please take a look.
> 
> Thanks,
> Benedikt

lgtm.

[Benedikt Meurer, 2015-08-13 09:38:59]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-08-13 09:39:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1291973002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1291973002/1

[commit-bot: I haz the power, 2015-08-13 09:41:40]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-13 09:42:06]

Patchset 1 (id:??) landed as
https://crrev.com/3d01d31fa94f7cda711c12735cb69a1fe795cc8d
Cr-Commit-Position: refs/heads/master@{#30148}