It's rarely used, so just using {compiler::WasmGraphBuilder} directly
is easier to understand and does not add much to the code length.

R=titzer@chromium.org

Bug: v8:8238
Change-Id: I8eafaac59295047a8540ebe256f00dff61ddae82
Reviewed-on: https://chromium-review.googlesource.com/c/1276426Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56571}