Called when going over a point decoration. The active range
decorations that cover the point and have a higher precedence
are provided in active. The open count in openStart counts
the number of those ranges that started before the point and. If
the point started before the iterated range, openStart will be
active.length + 1 to signal this.
Called for any ranges not covered by point decorations. active
holds the values that the range is marked with (and may be
empty). openStart indicates how many of those ranges are open
(continued) at the start of the span.
Methods used when iterating over the spans created by a set of ranges. The entire iterated range will be covered with either
spanorpointcalls.