The interpreter assumed that native context indices of the
runtime functions are less than 256, which is not the case if
intrinsics are at the end of the native context and we keep adding
fields to native context.

Also fix the operand type, so that we get a DCHECK failing if the ids
don't fall into the expected range.

Change-Id: I8bc13a90593739ec66cb0a507572cf5b2acc4235
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2129632
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66925}