Prevent to measure the whole word when break-word

Prevent to measure the whole word when break-word

crrev.com/385693 changed the line breaker to measure word-by-word then
rewind if break-word/break-all. This causes a performance regression
when a word is extraordinary long, such as minified JS/CSS or
hex/base64 data.

This patch fixes to measure character-by-character, but unlike before
r385693, it lets overflow by 2em then rewind to the correct position.

This prevents the line breaker to measure the whole word, while
still measuring ligatures/kernings correctly as long as the sum of
such effects is within 2em.

BUG=603398
Review URL: https://codereview.chromium.org/1900513002

Cr-Commit-Position: refs/heads/master@{#387974}
(cherry picked from commit 41fe145a8629f1f7002b41a8e12687b97d5e635f)

Committed: https://chromium.googlesource.com/chromium/src/+/7183255cb9dd01ff20a267c2b682d92feb6ad2a1

[kojii, 2016-04-20 15:14:35]

Description was changed from

==========
Prevent to measure the whole word when break-word

crrev.com/385693 changed the line breaker to measure word-by-word then
rewind if break-word/break-all. This causes a performance regression
when a word is extraordinary long, such as minified JS/CSS or
hex/base64 data.

This patch fixes to measure character-by-character, but unlike before
r385693, it lets overflow by 2em then rewind to the correct position.

This prevents the line breaker to measure the whole word, while
still measuring ligatures/kernings correctly as long as the sum of
such effects is within 2em.

BUG=603398

Review URL: https://codereview.chromium.org/1900513002

Cr-Commit-Position: refs/heads/master@{#387974}
(cherry picked from commit 41fe145a8629f1f7002b41a8e12687b97d5e635f)
==========

to

==========
Prevent to measure the whole word when break-word

crrev.com/385693 changed the line breaker to measure word-by-word then
rewind if break-word/break-all. This causes a performance regression
when a word is extraordinary long, such as minified JS/CSS or
hex/base64 data.

This patch fixes to measure character-by-character, but unlike before
r385693, it lets overflow by 2em then rewind to the correct position.

This prevents the line breaker to measure the whole word, while
still measuring ligatures/kernings correctly as long as the sum of
such effects is within 2em.

BUG=603398

Review URL: https://codereview.chromium.org/1900513002

Cr-Commit-Position: refs/heads/master@{#387974}
(cherry picked from commit 41fe145a8629f1f7002b41a8e12687b97d5e635f)

Committed:
https://chromium.googlesource.com/chromium/src/+/7183255cb9dd01ff20a267c2b682...
==========

[kojii, 2016-04-20 15:14:37]

Committed patchset #1 (id:1) manually as
7183255cb9dd01ff20a267c2b682d92feb6ad2a1.