Removed RootEditableElementOf(VisiblePosition&) from EditingUtilities.

This patch removed RootEditableElementOf(VisiblePosition&) from EditingUtilities.{cpp, h}
since now none of used RootEditableElementOf take VisiblePossition as its input.

Bug: 
Change-Id: I213bbdef6c623612485670a13bafae9e7b085940
Reviewed-on: https://chromium-review.googlesource.com/616366
Commit-Queue: Akari Asai <akariasai@google.com>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#495600}
1 file changed