REGRESSION(r175601): Assertion failures in SimpleLineLayout
https://bugs.webkit.org/show_bug.cgi?id=138422

Check for end.

* rendering/SimpleLineLayout.cpp:
(WebCore::SimpleLineLayout::FlowContentIterator::isNewlineCharacter):
(WebCore::SimpleLineLayout::removeTrailingWhitespace):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@175620 268f45cc-cd09-0410-ab3c-d52691b4dbfc