Restore the scroll in all frames before taking a screenshot.

Tests run in a subframe and `scrollIntoView` could scroll the parent frame, which could change the visible portion of the test frame.


Bug: 401489541
Change-Id: I4e167448f66d5ba54414c9a9ce369e048b876921
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6382080
Commit-Queue: Philip Pfaffe <[email protected]>
Auto-Submit: Danil Somsikov <[email protected]>
Reviewed-by: Philip Pfaffe <[email protected]>

Author: danilsomsikov

front_end/testing/DOMHelpers.ts

@@ -324,6 +324,11 @@ export function querySelectorErrorOnMissing<T extends HTMLElement = HTMLElement>
 export async function assertScreenshot(filename: string) {
   // To avoid a lot of empty space in the screenshot.
   document.getElementById(TEST_CONTAINER_ID)!.style.width = 'fit-content';
+  let frame: Window|null = window;
+  while (frame) {
+    frame.scrollTo(0, 0);
+    frame = frame.parent !== frame ? frame.parent : null;
+  }
   await raf();
   // @ts-expect-error see karma config.
   const result = await window.assertScreenshot(`#${TEST_CONTAINER_ID}`, filename);