fix selection painting of empty lines if text area displays line numbers

Author: DevCharly

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

@@ -270,7 +270,7 @@ private PathElement[] getRangeShapeSafely(int start, int end) {
             // Selection includes a newline character.
             if (paragraph.length() == 0) {
                 // empty paragraph
-                shape = createRectangle(getLayoutX(), getLayoutY(), getWidth(), getHeight());
+                shape = createRectangle(0, 0, getWidth(), getHeight());
             } else if (start == paragraph.length()) {
                 // selecting only the newline char