Able to reproduce the issue on windows-10, Linux Ubuntu 14.04 and Mac 10.11.4 using chrome stable version 53.0.2785.143, beta 54.0.2840.59 and latest canary 55.0.2889.0.

This is regression issue broken in M49.Please find the bisect information as below
Narrow Bisect::
===============
Good :: 49.0.2573.0  --   (build revision 361233)
Bad:: 49.0.2574.0 --   (build revision 361527)

ChangeLog: https://chromium.googlesource.com/chromium/src/+log/206123a4b6cb14a8da596d2120761f1beda972fc..fa7fc32c5940dfd3d734ed3231b1295da4c3303e
================

Possible suspect
==================
fa7fc32c5940dfd3d734ed3231b1295da4c3303e

Review URL: https://codereview.chromium.org/1474673003


eae@ could you please look into this issue if it is related to your change,else please help us in finding the appropriate owner for this issue.

Thanks,

Please do not assign bugs directly to engineers. It will get looked at much quicker if you let it go through the normal triage process.

This appears to be a problem with break-word where we measure the first character "Д" and then the subsequent string "оговор" separately and add up the values. This turns out to be less than the total width.

Koji, you know the break-all/word code pretty well. Would you mind taking a look?

See attached minimal test case.

Deleted: ru.html 338 bytes

ru.html 338 bytes View Download

The "white-space: pre-line" is a new combination that wasn't taken care of in the last fix. The test works good without it, interesting to know pre-line can break this scenario.

Preferred width has been wrong, but it only appears in the layout result when "white-space: pre-wrap" or "white-space: pre-line".

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/715e724f5eb62b3517f093cadf5716e0fb3040ea

commit 715e724f5eb62b3517f093cadf5716e0fb3040ea
Author: kojii <kojii@chromium.org>
Date: Sat Oct 22 01:35:22 2016

Fix max preferred width for LayoutText when break-all

This patch fixes max preferred width for LayoutText when break-all
preferred width ("word-break: break-all" or "word-break: break-word")
is used.

The problem only appears when the sum of character widths is not equal
to the word width. However, when the sum is larger (e.g., kerning,) the
difference is hardly noticeable.

Also an optimization in LayoutText::width() hides the problem when
!preserveNewline(), so it is visible only when "white-space: pre-wrap"
or "white-space: pre-line".

BUG= 655590 

Review-Url: https://chromiumcodereview.appspot.com/2438683006
Cr-Commit-Position: refs/heads/master@{#426946}

[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/fast/css3-text/css3-word-break/word-break-all-rtl-expected.txt
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/fast/css3-text/css3-word-break/word-break-all-rtl.html
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/linux/fast/text/word-break-soft-hyphen-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/linux/fast/text/word-break-soft-hyphen-expected.txt
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac-mac10.10/fast/text/word-break-run-rounding-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac-mac10.10/fast/text/word-break-soft-hyphen-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac-mac10.9/fast/text/word-break-run-rounding-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac-mac10.9/fast/text/word-break-soft-hyphen-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac/fast/text/word-break-run-rounding-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac/fast/text/word-break-run-rounding-expected.txt
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac/fast/text/word-break-soft-hyphen-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/mac/fast/text/word-break-soft-hyphen-expected.txt
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/win/fast/text/word-break-soft-hyphen-expected.png
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/LayoutTests/platform/win/fast/text/word-break-soft-hyphen-expected.txt
[modify] https://crrev.com/715e724f5eb62b3517f093cadf5716e0fb3040ea/third_party/WebKit/Source/core/layout/LayoutText.cpp

 Issue 665426  has been merged into this issue.

r426946 seems to break another use case, see  issue 687338 .