Update mixed-decl tests to reflect the improved implementation (#2014) #1572

Job	Run time
Lint spec files	15s
JS API \| Pure JS \| Browser	1m 21s
Language \| Dart Sass \| Dart stable	1m 0s
JS API \| Pure JS \| Node lts/* \| ubuntu-latest	1m 19s
Language \| Dart Sass \| Dart dev	59s
JS API \| Embedded \| Node lts/* \| ubuntu-latest	4m 52s
JS API \| Pure JS \| Node lts/* \| windows-latest	3m 15s
Static analysis	17s
JS API \| Embedded \| Node lts/* \| windows-latest	6m 37s
JS API \| Pure JS \| Node lts/* \| macos-latest	1m 7s
JS API \| Embedded \| Node lts/* \| macos-latest	3m 34s
Unit tests	37s
JS API \| Pure JS \| Node lts/-1 \| ubuntu-latest	1m 16s
JS API \| Embedded \| Node lts/-1 \| ubuntu-latest	4m 56s
JS API \| Pure JS \| Node lts/-2 \| ubuntu-latest	1m 23s
JS API \| Embedded \| Node lts/-2 \| ubuntu-latest	5m 4s
JS API \| Pure JS \| Node lts/-3 \| ubuntu-latest	1m 31s
JS API \| Embedded \| Node lts/-3 \| ubuntu-latest	1m 40s
	41m 3s

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