Add GetIdentityHash to v8::Name object API

v8::Object already has GetIdentityHash on it. This change adds its counterpart to v8::Name.

BUG=chromium:437416
LOG=Y

Review URL: https://codereview.chromium.org/753373003

Cr-Commit-Position: refs/heads/master@{#25598}
Fix idle time trace printing.

BUG=
R=jochen@chromium.org

Review URL: https://codereview.chromium.org/771123002

Cr-Commit-Position: refs/heads/master@{#25599}
[turbofan] Make context specialization into a reducer.

R=bmeurer@chromium.org
BUG=

Review URL: https://codereview.chromium.org/771713002

Cr-Commit-Position: refs/heads/master@{#25600}
Parser: Removing debug code.

The mystery crash never reappeared once the debugging code was in place.

R=jochen@chromium.org
BUG=

Review URL: https://codereview.chromium.org/760863003

Cr-Commit-Position: refs/heads/master@{#25601}