Font ligatures do not work with accessibilitySupport

[armoha]

• VSCode Version: 1.36.1
• OS Version: Windows 10 Education x64 (Build 17763.615)

Steps to Reproduce:

1. Install font with ligatures (e.g. Fira Code) and write settings.json as follows:

{
  "editor.fontFamily": "Fira Code",
  "editor.fontLigatures": true,
  "editor.accessibilitySupport": "on",
}

2. Ligatures do not work when "editor.accessibilitySupport" is "on". Ligatures work when it is "off".

Does this issue occur when all extensions are disabled?: Yes