The set of registers to spill was wrong. Instead of spilling wasm
parameter registers (like the WasmCompileLazy builtin), we should spill
all registers that are being used as Liftoff cache registers.
This CL defines platform-specific WasmDebugBreakFrameConstants which
hold the set of registers to spill. This set is used in the builtin, and
will later be used for inspecting the spilled registers.

In order to iterate bit sets more easily in both direction (MSB to LSB
or LSB to MSB), we add a base::bits::IterateBits{,Backwards} method
which provides the respective iterators.

R=jkummerow@chromium.org
CC=thibaudm@chromium.org

Bug: v8:10222
Change-Id: I73ecbdff9b29e244c478b404063c0c9ee25bc821
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2102570Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66715}