Umlauts in Firefox

[thisancog]

While font rendering is fine in Webkit browsers I found the display of the "ü" character in Firefox 52.0 erroneous. I included Mukta (font-weight: 200) via its GoogleFonts repository, but while it works in Typecast, the position of the Trema is shifted to the right on other websites for certain character combinations. Weirdly enough, it works sometimes well. See attached screenshot:

[gasyoun]

position of the Trema is shifted

So it's a pure scripting bug, undocumented

[girish-dalvi]

@thisancog I am unable to reproduce this bug. Please share the text file for the test case and the details of the operating system.