LineBuilder is responsible for adding content to the line but the alignment (horizontal/vertical) should be done by the LineBox.
Created attachment 405681 [details] Patch
<rdar://problem/66675537>
Created attachment 407309 [details] Patch
Created attachment 407319 [details] Patch
ChangeLog entry in Source/WebCore/ChangeLog is not at the top of the file.
Created attachment 407369 [details] Patch
Committed r266222: <https://trac.webkit.org/changeset/266222> All reviewed patches have been landed. Closing bug and clearing flags on attachment 407369 [details].