Handlify JSObject::MigrateInstance and friends.

Handlify JSObject::MigrateInstance and friends.

This relands the original change from r16899 together with a bugfix for
two unhandlified values which became stale.

R=verwaest@chromium.org
TEST=mjsunit/debug-evaluate-locals-optimized (in GC stress mode)

Committed: http://code.google.com/p/v8/source/detail?r=16905

[Michael Starzinger, 2013-09-23 18:04:26]

Review instructions:
- Patch set #1: Dupe of https://codereview.chromium.org/23583052/
- Patch set #2: The actual fix to be able to reland.

[Toon Verwaest, 2013-09-23 19:24:18]

doh! lgtm.

[Michael Starzinger, 2013-09-23 19:56:48]

Committed patchset #2 manually as r16905 (presubmit successful).