Fix visualiser after virtualisation

Summary: There was an issue with cropping introduce by virtualisation and the position of the scroll view in the hierachy. Its a bit fragile but it works now.

Reviewed By: lblasa

Differential Revision: D46761831

fbshipit-source-id: ce001c6f4fe7ddc111edf0098f75a1273c84472d

desktop/plugins/public/ui-debugger/components/Visualization2D.tsx

@@ -111,6 +111,9 @@ export const Visualization2D: React.FC<
         //this div is to ensure that the size of the visualiser doesnt change when focusings on a subtree
         style={
           {
+            overflowY: 'auto',
+            overflowX: 'hidden',
+            position: 'relative', //this is for the absolutely positioned overlays
             [pxScaleFactorCssVar]: pxScaleFactor,
             width: toPx(focusState.actualRoot.bounds.width),
             height: toPx(focusState.actualRoot.bounds.height),