This is from https://chromium-review.googlesource.com/c/chromium/src/+/989474

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0d80add3eca040d94a5f7177034f8132652bb9ee

commit 0d80add3eca040d94a5f7177034f8132652bb9ee
Author: Koji Ishii <kojii@chromium.org>
Date: Mon Apr 02 12:17:38 2018

LayoutText::LocalSelectionRect should return early if range is invalid

While working on supporting LayoutNG, it turns out that there are
several cases where the selection range becomes start > end.
  e.g., fast/text/selection/emphasis.html

Layout functions generally prefer proper checks are done in the
callers, rather than input arguments automatically corrected in
lower-level functions.

This patch makes LayoutText::LocalSelectionRect match to it.

Bug: 636993,  827925 
Change-Id: I3068e70886f7cd425a2fd5f701ac0b7d77a8a978
Reviewed-on: https://chromium-review.googlesource.com/989474
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547430}
[modify] https://crrev.com/0d80add3eca040d94a5f7177034f8132652bb9ee/third_party/WebKit/Source/core/layout/LayoutText.cpp