"Nested" dialogs (template inside a basic reference) break the OOUI hack to prevent scrolling while dialog is open (added in 4d87bde4495e5204b722d2154885f9c127ad30e3 / https://gerrit.wikimedia.org/r/#/c/179598/).

To reproduce:

• View https://en.wikipedia.org/wiki/Skyfall#Casting, open VisualEditor
• Open the first reference in this section (currently numbered [17], [15] in VE probably due to T52474)
  • Observe that window scrollbar disappears.
  • Observe that the window scrolls slightly (T89612).
• The reference has two templates in it; open either one
• Close the "nested" dialog
  • Observe that the scrollbar has incorrectly reappeared, while it should only reappear after the "parent" dialog is closed.
  • Observe that the position of the blue highlight on the [15] is not updated.