isBlockingSemanticsOfPreviouslyPaintedNodes property Null safety
If set to true, the semantic information for all siblings and cousins of this node, that are earlier in a depth-first pre-order traversal, are dropped from the semantics tree up until a semantic boundary (as defined by isSemanticBoundary) is reached.
If isSemanticBoundary and isBlockingSemanticsOfPreviouslyPaintedNodes is set on the same node, all previously painted siblings and cousins up until the next ancestor that is a semantic boundary are dropped.
Paint order as established by RenderObject.visitChildrenForSemantics is used to determine if a node is previous to this one.
bool isBlockingSemanticsOfPreviouslyPaintedNodes = false;