No more LazyReattachIfAttached in slot DetachLayoutTree.

We now call DetachLayoutTree like the comment said. Replace if-guard
with a DCHECK. The same goes for V0InsertionPoint.

Change-Id: I7bd20c5ae9dc98b571876a87dd98ccb0225d2248
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1520676
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640687}
1 file changed