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.

Review URL: https://codereview.chromium.org/796503002

Cr-Commit-Position: refs/heads/master@{#25763}