Issue 618178  exposes an issue with our font fallback code not finding a good font fallback font if the unshaped segment starts with script common characters. The fallback font is then not specific enough in many cases, leading to .notdefs for example for this Myanmar example.

We should probably move the fix from this issue down into our font code and put higher weight/importance on the script information when finding a fallback font.

This affects Mac with higher priority since it does not seem to take into account the locale information from the page for font fallback.