[menu-surface]: Toggling hoistToBody doesn't work as expected

[austinw-fineart]

Describe the bug
Enabling and then disabling hoistToBody does not restore the menu element to its original position. Additionally, destroying the component after toggling while leaving hoistToBody disabled will leak the element.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://trimox.github.io/angular-mdc-web/#/angular-mdc-web/menu-surface/examples
2. Click on 'Show Menu Surface' and scroll the page
3. Toggle 'Hoist to Body' on and off
4. Click on 'Show Menu Surface' again and scroll the page (or inspect the element)

Expected behavior
Disabling hoistToBody should restore the menu element to its original position.

What Angular MDC version are you using?
v6.0.0-canary.9
What OS are you using?:
Windows 10
What browser(s) is this bug affecting?:
All