Solves two problems:
1. Fix the debug crash by restoring the clip after the `EntityPass`
merge. I initially surrounded the merge with a `Save` and `Restore`,
which was a mistake and is a no-op in this situation. This should have
no excess impact on performance, since we ignore clips in `EntityPass`
when we detect that they won't do anything.
2. Picture subpasses weren't getting their stencil depth adjusted during
the merge, which can result in subpass entities potentially receiving a
clip depth that's too high.
d6ab095556