SF: Fix Region log spam

When calulating geometry if the layer has no buffer (i.e. it is a color
layer), it will not have a size. In this case skip operations to mark
regions outside of crop area as transparent.

Test: adb logcat search for spam log + go/wm-smoke + unit tests

Change-Id: I3ba7b770d0746a663dcdfc464db17ccaa7ca4241