55                 // check if the shape subtracted either contains the entire bounds (and makes  in reduced_stack_walker()
77                 // check if the shape intersected contains the entire bounds and therefore can  in reduced_stack_walker()
100                 // If the union-ed shape contains the entire bounds then after this element  in reduced_stack_walker()
101                 // the bounds is entirely inside the clip. If the union-ed shape is outside the  in reduced_stack_walker()
123                 // If the bounds is entirely inside the shape being xor-ed then the effect is  in reduced_stack_walker()
125                 // able to take advantage of this in the forward pass. If the xor-ed shape  in reduced_stack_walker()
145                 // When the bounds is entirely within the rev-diff shape then this behaves like xor  in reduced_stack_walker()
146                 // and reverses every point inside the bounds. If the shape is completely outside  in reduced_stack_walker()
170                 // at the replace op or detect here than the shape is either completely inside  in reduced_stack_walker()
215                 // Intersecting an inverse shape is the same as differencing the non-inverse shape.  in reduced_stack_walker()
216                 // Replacing with an inverse shape is the same as setting initialState=kAllIn and  in reduced_stack_walker()
217                 // differencing the non-inverse shape.  in reduced_stack_walker()
259                         // unioning the empty set with a shape is the shape.  in reduced_stack_walker()