Capture by MS test:
css/css-fonts/variations/font-stretch.html

FAIL @supports: calc(-100%) - Negative calc value (to be clamped) assert_equals: Negative calc value (to be clamped) expected true but got false
FAIL @getComputedStyle: calc(-100%) - Negative calc value (to be clamped) assert_equals: Negative calc value (to be clamped) expected "0%" but got "80%"
FAIL @supports: calc(50% - 50%*2) - Negative calc expression (to be clamped) assert_equals: Negative calc expression (to be clamped) expected true but got false
FAIL @getComputedStyle: calc(50% - 50%*2) - Negative calc expression (to be clamped) assert_equals: Negative calc expression (to be clamped) expected "0%" but got "80%"