Create optimized versions of the Map/Set clear method

Create optimized versions of the Map/Set clear method

This completes the first round of optimizations for Map and Set.
All non-key-dependent methods now have a Hydrogen version, and
for keyed methods, string versions are optimized.

[adamk, 2014-12-10 19:27:28]

adamk@chromium.org changed reviewers:
+ dslomov@chromium.org

[Dmitry Lomov (no reviews), 2014-12-10 19:29:43]

nice! lgtm

[adamk, 2014-12-10 21:49:15]

The CQ bit was checked by adamk@chromium.org

[commit-bot: I haz the power, 2014-12-10 21:49:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/796503002/1

[commit-bot: I haz the power, 2014-12-10 22:16:23]

Committed patchset #1 (id:1)