Also allow the empty object map to keep transitions.

Also allow the empty object map to keep transitions.

With the old implementation, due to the map-check being inadequate, such
transitions were already added for cross-context field stores. It is not
necessary anymore to not store transitions, since we properly clear
non-live transitions. Globally enabling this feature will help find more
bugs.

BUG=v8:2518
R=mstarzinger@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=13558

[Toon Verwaest, 2013-01-30 09:05:28]

PTAL

[Michael Starzinger, 2013-01-30 10:37:15]

LGTM (with one nit).

https://chromiumcodereview.appspot.com/12092063/diff/1/src/objects.cc
File src/objects.cc (right):

https://chromiumcodereview.appspot.com/12092063/diff/1/src/objects.cc#newcode...
src/objects.cc:1838: // with the map of "new Object()" cannot have transitions
in the first place.
This comment is also outdated. Drop the second sentence.

[Toon Verwaest, 2013-01-30 15:07:10]

Addressed comment, landing.