[touch-events] Re-add tests for extentions APIs (#21)

At one point we did have tests for radiusX, radiusY, force, rotationAngle and identifiedTouch but removed them when those were moved to the extensions note.  We should re-add them.

@SummerWW, are you interested in doing this (as part of your work on improving blink's use of W3C tests)?

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/touch-events/issues/21