Fix updating of property attributes for elements.

Fix updating of property attributes for elements.

This fixes updating of property attributes for data elements when
attributes are already present on a dictionary element but get removed
by a subsequent redefinition of that element.

R=rossberg@chromium.org
BUG=v8:1772
TEST=test262/15.2.3.6-4-82-18

Committed: http://code.google.com/p/v8/source/detail?r=9691

[Michael Starzinger, 2011-10-18 13:30:42]

PTAL.

[rossberg, 2011-10-19 09:01:39]

lgtm