Replace some ScrollingTreeNode::nodeType() calls with is*Node()
Created attachment 323661 [details] Patch
Note: I'm not sure yet, but this might be useful for bug 173833 if we introduce some new kind of FrameScrollingNode to handle non-main frames.
Committed r223337: <https://trac.webkit.org/changeset/223337>
<rdar://problem/35002387>