Add kRunningOnCompositorButNeedsAdjustment to DCHECK in WillAnimateToOffset

In some cases, ScrollAnimator::WillAnimateToOffset called with run_state_ ==
RunState::kRunningOnCompositorButNeedsAdjustment.

Bug: 825351
Change-Id: I805625d87d469c77564391c83d381eb179c665c8
Reviewed-on: https://chromium-review.googlesource.com/1033015Reviewed-by: Steve Kobes <skobes@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554790}

third_party/blink/renderer/platform/scroll/scroll_animator.cc

@@ -161,7 +161,8 @@ bool ScrollAnimator::WillAnimateToOffset(const ScrollOffset& target_offset) {
     DCHECK(run_state_ == RunState::kRunningOnMainThread ||
            run_state_ == RunState::kRunningOnCompositor ||
            run_state_ == RunState::kRunningOnCompositorButNeedsUpdate ||
-           run_state_ == RunState::kRunningOnCompositorButNeedsTakeover);
+           run_state_ == RunState::kRunningOnCompositorButNeedsTakeover ||
+           run_state_ == RunState::kRunningOnCompositorButNeedsAdjustment);
 
     // Running on the main thread, simply update the target offset instead
     // of sending to the compositor.