Chromiun no longer use set_sources_assignment_filter() anywhere in the
build, so these are no longer needed.

Bug: chromium:1018739
Change-Id: I7b33612d925563ebca0d93a7d3c9183d7305b7b0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2456988Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70405}