https://drafts.csswg.org/css-text-3/#letter-spacing-property "Because letter-spacing is not applied at the beginning or end of a line, text always fits flush with the edge of the block. UAs therefore must not append letter spacing to the right or trailing edge of a line:"
<rdar://problem/57545763>
Created attachment 384579 [details] Patch
Committed r252972: <https://trac.webkit.org/changeset/252972>