Issue by Hixie
Thursday June 23, 2015 at 19:55
Originally opened as domokit/mojo#264 then copied to https://github.com/flutter/engine/issues/46

The TrueType 'bsln' table exposes metrics for ideographic, hanging, and mathematical baselines. We should add support for those to FreeType and our other font backends, then add support to Skia to report these metrics, then add support to the Sky engine to be able to align to those baselines and report the distance from the top of a LayoutRoot to each of those baselines, then add support for those baselines to the Dart-level RenderBox baseline protocol.