convert kebab-case to camelCase in testProps for browsers that don't have @supports support
`testProp()` and `testAllProps()` now accept kebab-case – updating tests & comments to match
Merge pull request #4 from stucox/patrickkettner-fix-kebab-check

`testProp()` and `testAllProps()` now accept kebab-case – updating tests...
Merge pull request #1323 from patrickkettner/fix-kebab-check

convert kebab-case to camelCase in testProps for browsers that don't have @supports support