Instead of using the TextRun direction. If the TextRun is ltr, but the harfbuzz buffer is rtl, the character indexes will be swapped in m_coreTextIndices.
Created attachment 324814 [details] Patch
Comment on attachment 324814 [details] Patch ¯\_(ツ)_/¯
Committed r224007: <https://trac.webkit.org/changeset/224007>
<rdar://problem/35568097>