Adding 2 assertions: 1. assert that we don't index pass the end of the StructureIDTable. This should never happen, but this assertion will help catch bugs where a bad structureID gets passed in. 2. assert that cells in MarkedBlock::callDestructor() that are not zapped should have a non-null StructureID. This will help us catch bugs where the other cell header flag bits get set after the cell is zapped, thereby making the cell look like an unzapped cell but has a null structureID.
Created attachment 235910 [details] the patch
Comment on attachment 235910 [details] the patch r=me
Thanks. Landed in r171953: <http://trac.webkit.org/r171953>.