CsaLoadElimination failed to account for truncation when optimizing
loads. This CL extends the notion of compatible Loads and Stores to
include ({store}, {load}) pairs which both have integral representation
and {store}'s representation is no smaller than {load}'s. In case the
representations are not identical, it truncates and possibly
sign-extends {store} before forwarding it to {load}.

Additional change: Extend ObjectMayAlias with wasm allocating builtin
calls.

Bug: v8:11504
Change-Id: I43f89a13793b54477a33be18aaf346462aefa8e5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2739975Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73340}