Create chevron using pseudo elements

IE8+ supports the pseudo element. The world will not explode if
IE6 and 7 do not have the chevron.

This simplifies code by dropping the use of the pokey element

Note: I know we can drop using the image too but I decided not to do
that in this patch.

Change-Id: Ia9ac434461e63bc2cf8554060126995ac65a3531
Create notification overlay in the body

This removes the need from the super specific selectors.
It also allows us to create multiple notification elements
on a screen.

Change-Id: Ife5291a315915779689943ffc18ac73d77351d0e
E2f: mark all as read behaviour

Also adds browser tests for the behaviour of the mark all as read button
to ensure it only clears message notifications.

Dependency:  Ifb7b1b7b7feb4a5af65c79bb16b91a5a9c70166c
Change-Id: I46e1de229e32d705e67cebde678ecea3f3633906
Merge "E2f: mark all as read behaviour" into two_tabs
Merge remote-tracking branch 'gerrit/two_tabs'

Change-Id: Ie2c7abd1df09c501e86c6ef4c22fd8670163de4c
Merge "Merge remote-tracking branch 'gerrit/two_tabs'"