Remove `@-moz-document`-specific specs (#2035) #1649

Job	Run time
Language \| Dart Sass \| Dart stable	1m 6s
Language \| Dart Sass \| Dart dev	1m 5s
JS API \| Embedded \| Node lts/* \| ubuntu-latest	4m 59s
JS API \| Embedded \| Node lts/* \| windows-latest	6m 23s
JS API \| Pure JS \| Node lts/* \| ubuntu-latest	1m 23s
JS API \| Pure JS \| Browser	1m 19s
JS API \| Embedded \| Node lts/* \| macos-latest	4m 18s
JS API \| Pure JS \| Node lts/* \| windows-latest	3m 22s
JS API \| Pure JS \| Node lts/* \| macos-latest	1m 13s
JS API \| Embedded \| Node lts/-1 \| ubuntu-latest	4m 50s
Lint spec files	17s
Static analysis	19s
JS API \| Pure JS \| Node lts/-1 \| ubuntu-latest	1m 23s
JS API \| Embedded \| Node lts/-2 \| ubuntu-latest	5m 5s
JS API \| Pure JS \| Node lts/-2 \| ubuntu-latest	1m 26s
JS API \| Embedded \| Node lts/-3 \| ubuntu-latest	5m 6s
Unit tests	37s
JS API \| Pure JS \| Node lts/-3 \| ubuntu-latest	1m 47s
	45m 58s

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