[REG: 5.9->5.10]: If the next item in tab order after tab widget is the last child item of that tab, there is a crash when destructing the tab widget

If tab widget has child items, and the next child item in tab order after the tab widget itself, is the last child item in the tab's children list, destructing that widget crashes.

Steps to reproduce:

• Run attached sample
• Close the application
• EXPECTED: Application destructs properly
• ACTUAL: Application crashes (see attached image)

The crash can be prevented by switching the tab order of the two inner buttons (2 and 3) in .ui file:
From

 <tabstops>
  <tabstop>pushButton_4</tabstop>
  <tabstop>tabWidget</tabstop>
  <tabstop>pushButton_3</tabstop>
  <tabstop>pushButton_2</tabstop>
 </tabstops>

To

 <tabstops>
  <tabstop>pushButton_4</tabstop>
  <tabstop>tabWidget</tabstop>
  <tabstop>pushButton_2</tabstop>
  <tabstop>pushButton_3</tabstop>
 </tabstops>

Or by simply moving the pushButton_3 child item before the pushButton_2 child item in tab_2's widgets list.