This CL removes the graph between phase changes. This prevents incorrect
path layouting after changing from a phase where a path is displayed that
is not a correct path in the phase we change to.

Change-Id: Iad80f49efc8d8c71600ad51432981c3a206ef9cb
Bug: v8:7327
Reviewed-on: https://chromium-review.googlesource.com/c/1397710Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58592}