The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8d1974aecc77d407a9ee89d2434f0079b4cc1e40

commit 8d1974aecc77d407a9ee89d2434f0079b4cc1e40
Author: xiaochengh <xiaochengh@chromium.org>
Date: Wed Aug 24 02:15:54 2016

Force expandToParagraphBoundary to return a valid EphemeralRange

This is a first-aid patch that make expandToParagraphBoundary()
compare the paragraph boundaries found with the input range before
returning, so that the returned range is always a super-range of
the input range, and hence, a valid EphemeralRange.

This patch does not fix the root cause of the bugs, as we:
- do not expect startOfParagraph()'s return value to be beyond that of
endOfParagraph()'s, and
- are planning of getting rid of TextCheckingParagraph, the only client
of expandToParagraphBoundary(), ultimately

BUG= 639521 ,  639801 ,  640022 ,  640030 ,  640112 
TEST=n/a; this is a first-aid patch

Review-Url: https://codereview.chromium.org/2271603002
Cr-Commit-Position: refs/heads/master@{#413942}

[modify] https://crrev.com/8d1974aecc77d407a9ee89d2434f0079b4cc1e40/third_party/WebKit/Source/core/editing/spellcheck/TextCheckingParagraph.cpp