Fix horizontal scrolling excessive layouts (#1296)

Author: Jugen

richtextfx/src/main/java/org/fxmisc/richtext/CaretNode.java

@@ -231,7 +231,7 @@ public CaretNode(String name, GenericStyledArea<?, ?, ?> area, SuspendableNo dep
 
         bounds = Val.create(
                 () -> area.getCaretBoundsOnScreen(this),
-                EventStreams.merge(area.viewportDirtyEvents(), dirty)
+                invalidationsOf(paragraphIndex)
         ).suspendable();
 
         lineIndex = Val.create(