ASSERTION FAILED: v.isFixed() in WebCore::RenderStyle::setWordSpacing

https://bugs.webkit.org/show_bug.cgi?id=126987

Reviewed by Simon Fraser.

When "inherit" is specified and there is no parent, Length values have an "Auto" type

Source/WebCore:

Test: fast/css3-text/css3-word-spacing-percentage/word-spacing-crash.html

* rendering/style/RenderStyle.cpp:
(WebCore::RenderStyle::setWordSpacing):

LayoutTests:

* fast/css3-text/css3-word-spacing-percentage/word-spacing-crash-expected.txt: Added.
* fast/css3-text/css3-word-spacing-percentage/word-spacing-crash.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162588 268f45cc-cd09-0410-ab3c-d52691b4dbfc