Revert "Merge pull request #708 from mpriour/displayEvent"

This reverts commit 0b3f582e1030b9e9211e6098799fcdf9bd3e1ab1, reversing
changes made to 74103ec3e017c8c66ee3ae8f0a7c891c2a2cdd86.

The reason for reverting this is a regression. See #997.
Merge pull request #1003 from openlayers/notilemgrtest

Whenever we run tests *with* the tileManager, we cannot inspect any grid...(r=@ahocevar)