Follows-up 383a818.
* There is no need for the additional element ("a") or
descendant ("#pt-mytalk") selector.
It isn't overrriding anything, only hardcodes details that make
it harder to maintain or extend this stylesheet. For example,
there is a gadget that makes user messages green instead of
orange, it now was required to hardcode the "#pt-mytalk a" part
of the selector eventhough those are subject to change.
Separation of concerns.
* Cache/reuse the jQuery object instead of executing the same
query to the document, again. It also avoids a potential bug
where the second query matches different elements (e.g. after
appending alertMessage, there could potentially be an additional
nested anchor link; there isn't now though, as the message is
plain text).
* Add comment about weird echoNewMsgAlertDisplayed variable.
Change-Id: I682182fe15a868969f25fa5bfe2412e2a6f3dddf
72c8aba10e