This CL adds a LocationReference specifically for slices to Torque. This allows us to safely reference arrays in objects and pass around such references. For an array of T-typed elements, referencing yields a Slice<T>. In addition, the traditional element access syntax ('o.array[i]') now internally produces a slice, indexes it at 'i' and dereferences the resulting HeapReference.

Bug: v8:7793
Change-Id: I4af58e4d2feac547c55a1f6f9350a6c510383df2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1771782
Commit-Queue: Georg Schmid <gsps@google.com>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63479}