Add a performance test for arabic line breaking
https://bugs.webkit.org/show_bug.cgi?id=108948

Reviewed by Eric Seidel.

Adding a perfomance test based to exercise the complex
font path used in rendering arabic script.

* Layout/ArabicLineLayout.html: Added.
* Skipped: New test skipped by default as per Ryosuke's request.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141906 268f45cc-cd09-0410-ab3c-d52691b4dbfc