Add tessellation path for points

bug:4351353
bug:8185479

Point tessellation is similar to line special case, except that we
only tessellate one point (as a circle or rect) and duplicate it
across other instances.

Additionally:

Fixes square caps for AA=false lines

Cleanup in CanvasCompare, disabling interpolation on zoomed-in
comparison view

Change-Id: I0756fcc4b20f77878fed0d8057297c80e82ed9dc