Remove DWC from DistillPage

Data reveal that the double navigation is the true cause of the crash.
Handle this case gracefully and replace other DWC with CHECK.

Fixed: 328442655
Change-Id: I7922b988329666c7221eccb3fdcfa50c8246c165
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5458756
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1288712}