instances correctly

Revert changes of bug 549818 and also the now unneeded workaround of
550986:
https://git.eclipse.org/r/#/c/147881/
https://git.eclipse.org/r/#/c/150641/

Add a new regression test for the 1:1 relationship between MMenu
and MenuManager in MenuManagerRenderer.

Change-Id: Idc3203ecb1533c18e7cea7ac542d4d391a70cc91