[bug mat-menu]: nested menu not closing when mat-menu-item is not directly inside mat-menu

[sousarka]

Bug, feature request, or proposal:

Bug

What is the expected behavior?

nested menu should be closing when hovering out

What is the current behavior?

nested menu not closing when hovering out

What are the steps to reproduce?

Providing a StackBlitz reproduction is the best way to share your issue.

https://menu-with-tooltip.stackblitz.io

Once you open the "Invertebrates" nested menu, it'll stay open even if you hover over to "Molluscs" menu item.

What is the use-case or motivation for changing an existing behavior?

Would like to show a tooltip on a disabled menu-item. The tooltip will describe why the menu-item is disabled.

Which versions of Angular, Material, OS, TypeScript, browsers are affected?

Angular 5.2.5
Material 5.2.1

Is there anything else we should know?

[crisbeto]

Reopening the issue, because we had to revert the fix due to some unforeseen consequences.