Fix RemoveFromScrollTree and RemoveFromClipTree

These functions should set needs commit, but didn't. This lead to stale
pointers in the impl tree.

BUG=413743,403866
TBR=danakj@chromium.org

Review URL: https://codereview.chromium.org/572483002

Cr-Commit-Position: refs/heads/master@{#294749}
(cherry picked from commit 66133e86b6d79534605539aa684a248e6b6205bf)

Review URL: https://codereview.chromium.org/572353003

Cr-Commit-Position: refs/branch-heads/2125@{#390}
Cr-Branched-From: b68026d94bda36dd106a3d91a098719f952a9477-refs/heads/master@{#290040}
4 files changed