Should use `testProp()` here rather than `testProps()`, and it should be in the dependency list instead of `'createElement'` too.

`testProps()` is internal really (I appreciate [the naming is confusing](https://github.com/Modernizr/Modernizr/issues/824)).

Also, if you pull from master, now that #933 has landed we can use this syntax so that native detection kicks in where available: `testProp('textShadow', '1px 1px')`.