Adds new `br_on_cast <branch depth> <heap type>` instruction
with opcode 0xfb42.
The instruction does not branch on null.
The heap type may be any concreate heap type index or an abstract
type like `(ref null eq)`.
Bug: v8:7748
Change-Id: Id1d238645c176b32b568249d67fa28517b435ad4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4069559
Auto-Submit: Matthias Liedtke <mliedtke@chromium.org>
Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Matthias Liedtke <mliedtke@chromium.org>
Cr-Commit-Position: refs/heads/main@{#84598}
f06b360249