Even more id overflow in sroa (#2806)

Now we need to handle id overflow when we overflow while replacing uses of the variable.  While looking at this code, I noticed an error in the way we handle access chains that cannot be replaced because of overflow.  Name it will make some change, and then give up by returning SuccessWithoutChange.  But it was changed.

This is fixed up by returning Failure if we notice the error at the time of rewriting the users.  This is for both id overflow or out-of-bounds accesses.

Code is added to "CheckUses" to remove variables that have out-of-bounds accesses from the candidate list, so we don't even try to rewrite its uses.

Fixes https://crbug.com/995032