Include tab character as a word end for kerning
https://bugs.webkit.org/show_bug.cgi?id=115915
<rdar://problem/13861491>

Reviewed by Enrica Casucci.

This is a follow-up to https://bugs.webkit.org/show_bug.cgi?id=112507
which only looked for a space character as a word end. It should
look for tab characters too.

Source/WebCore:

Test: fast/text/word-space-with-kerning-4.html

* rendering/RenderBlockLineLayout.cpp:
(WebCore::setLogicalWidthForTextRun): Look for '\t'.

LayoutTests:

* fast/text/word-space-with-kerning-4-expected.html: Added.
* fast/text/word-space-with-kerning-4.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149891 268f45cc-cd09-0410-ab3c-d52691b4dbfc