Fix handle zapping interaction with NoHandleAllocation.

Fix handle zapping interaction with NoHandleAllocation.

This makes sure that closed handle scopes are properly zapped even if an
enclosing NoHandleAllocation shrunk the limit. It also unifies the code
that performs scope closing for internal and external handle scopes.

R=svenpanne@chromium.org
TEST=cctest/test-api/NestedLockersNoTryCatch

Review URL: https://codereview.chromium.org/16004006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14876 ce2b1a6d-e550-0410-aec6-3dcde31c8c00