fix the float Rect in OpenGLRenderer to handle NANs

- we want functions like isEmpty() to return true if NANs are
involved in the Rect

- also clean-up the intersect familly of calls

- minor cleanup in the int32_t Rect as well

These played a role in http://b/5331198.

Bug: 5331198

Change-Id: I5369725ab482e4b83da9f1bd4cee5256e5de75b2