I don't think it will be possible to avoid splitting fragments in the
presence of `vertical-align`, because one `ScannedTextFragment` could
potentially be split into arbitrary many fragments, each having its own
vertical position that can influence layout of other fragments.
This code also removes parts of `Range` that were no longer used.
r? @glennw
Source-Repo: https://github.com/servo/servo
Source-Revision: 799d0de0c09420a9657a6a7b5fb814374da31163
