Deduplicate the getXY helper function in the highlight editor integration tests

The helper function is available in `test_utils.mjs` since commit
301f1bb, so by exporting it there it can be reused.

test/integration/highlight_editor_spec.mjs

@@ -22,6 +22,7 @@ import {
   getRect,
   getSerialized,
   getSpanRectFromText,
+  getXY,
   kbBigMoveLeft,
   kbBigMoveUp,
   kbFocusNext,
@@ -60,11 +61,6 @@ const waitForPointerUp = page =>
 
 const switchToHighlight = switchToEditor.bind(null, "Highlight");
 
-const getXY = async (page, selector) => {
-  const rect = await getRect(page, selector);
-  return `${rect.x}::${rect.y}`;
-};
-
 describe("Highlight Editor", () => {
   describe("Editor must be removed without exception", () => {
     let pages;

test/integration/test_utils.mjs

@@ -901,6 +901,7 @@ export {
   getSelector,
   getSerialized,
   getSpanRectFromText,
+  getXY,
   hover,
   isCanvasWhite,
   isVisible,