Merge getLineAtIndex into RenderBlock::lineAtIndex
https://bugs.webkit.org/show_bug.cgi?id=106379

Reviewed by Eric Seidel.

getLineAtIndex can be merged into lineAtIndex, which was it's only caller.

No new tests, just refactoring.

* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::lineAtIndex):
(WebCore::RenderBlock::lineCount):
* rendering/RenderBlock.h:
(RenderBlock):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@139135 268f45cc-cd09-0410-ab3c-d52691b4dbfc