This allows to reset the layout to the the inital layout of the graph,
which only contains the control nodes.

Change-Id: I7ab9fb1615057df99983369cd0fcdd42a68e1924
Notry: true
Bug: v8:7327
Reviewed-on: https://chromium-review.googlesource.com/c/1409436
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58814}