text: Refactor EditText.line_text

This refactor takes advantage of the
new layout structure to simplify code.

core/src/display_object/edit_text.rs

@@ -1916,23 +1916,18 @@ impl<'gc> EditText<'gc> {
     pub fn line_text(self, line: usize) -> Option<WString> {
         let read = self.0.read();
         let line = read.layout.lines().get(line)?;
+        let text = read.text_spans.text();
 
-        let mut text = WString::new();
-        for layout_box in read.layout.boxes_iter() {
-            if layout_box.bounds().offset_y() < line.offset()
-                || layout_box.bounds().extent_y() > line.extent()
-            {
-                continue;
-            }
-
+        let mut line_text = WString::new();
+        for layout_box in line.boxes_iter() {
             if let LayoutContent::Text { start, end, .. } = layout_box.content() {
-                if let Some(box_tex) = read.text_spans.text().slice(*start..*end) {
-                    text.push_str(box_tex);
+                if let Some(box_tex) = text.slice(*start..*end) {
+                    line_text.push_str(box_tex);
                 }
             }
         }
 
-        Some(text)
+        Some(line_text)
     }
 
     fn execute_avm1_asfunction(