[cleanup] Use common helper

As discussed the was overlooked an should use the helper class,
for consistency

Bug: none
Change-Id: Ib617ab93cdcc7d141e1c4f977e66071441a818b6
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7096060
Auto-Submit: Nikolay Vitkov <[email protected]>
Reviewed-by: Ergün Erdoğmuş <[email protected]>
Commit-Queue: Nikolay Vitkov <[email protected]>
Commit-Queue: Ergün Erdoğmuş <[email protected]>

Author: Lightning00Blade

front_end/ui/components/tooltips/Tooltip.ts

@@ -443,7 +443,7 @@ export class Tooltip extends HTMLElement {
     this.#previousAnchorRect = anchorRect;
     this.#previousPopoverRect = currentPopoverRect;
 
-    const inspectorViewRect = UI.InspectorView.InspectorView.instance().element.getBoundingClientRect();
+    const inspectorViewRect = UI.UIUtils.getDevToolsBoundingElement().getBoundingClientRect();
     const preferredPositions =
         this.preferSpanLeft ? [PositionOption.BOTTOM_SPAN_LEFT, PositionOption.TOP_SPAN_LEFT] : [];
     const proposedPopoverRect = this.variant === 'rich' ?