The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0806cebf7d106f3514f94f9ef068026224da8777

commit 0806cebf7d106f3514f94f9ef068026224da8777
Author: David Tseng <dtseng@chromium.org>
Date: Fri Dec 01 20:01:56 2017

Treat lines that cover all of a node's text similarly to an object

Currently, line ranges use a slightly different output path when they
- have start/end on the same node
 - cover the node's text i.e. are not index -1 (node
index)

This change makes it so that we don't consider the range less than a node or use
the |subNode| output path if the range surrounds the entire node's text.

Test: navigate by lines (Search+up/down) over checkboxes. Output should be the
same as Search+Left/Right.

chromevox_tests --gtest_filter=Background*.* cover caret navigation and ensuring
they still work.

Bug:  784693 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I0404e11e326116e21afc2c9131a2ceeedf21e37c
Reviewed-on: https://chromium-review.googlesource.com/798370
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521026}
[modify] https://crrev.com/0806cebf7d106f3514f94f9ef068026224da8777/chrome/browser/resources/chromeos/chromevox/cvox2/background/background_test.extjs
[modify] https://crrev.com/0806cebf7d106f3514f94f9ef068026224da8777/chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.js