MatchesGoldenFileWithPixelAllowance constructor
Creates a MatchesGoldenFileWithPixelAllowance that looks for a golden
file at the relative path within the key URI.
The key URI should be a relative path from the executing test's
directory to the golden file, e.g., "goldens/my-golden-name.png".
Implementation
MatchesGoldenFileWithPixelAllowance(super.key, this._maxPixelMismatchCount, [super.version]);