Clean up Ganesh path render a little bit

Clean up Ganesh path render a little bit

I'm not sure if this is an improvement but this is an attempt to start moving the handling of pathEffects up the call stack (ideally to SkGpuDevice).

Note that the duplicate path sniffing in GrDrawContext::drawPath is still useful since it can be invoked if a path has to be explicitly drawn for a mask filter.

Review URL: https://codereview.chromium.org/1472333003