Adds a missing check that the elements kind of the boilerplate object
still has the expected elements kind, unoptimized code can transition
the boilerplate. Corner cases might cause the optimized code to be
reentered again.

R=danno@chromium.org
TEST=mjsunit/regress/regress-fast-literal-transition

Review URL: https://chromiumcodereview.appspot.com/10254006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11470 ce2b1a6d-e550-0410-aec6-3dcde31c8c00