Note that in the code, and still, has_curl_request was always false.
However, instead of deleting all code paths that are only executed
when has_curl_request would be true, I fixed the code to work as
intended with my current implementation; which also results in
LLCurlRequests to never expire. This way things won't break
unexpectedly when this ever changes.
Since on this branch isValid was only called still (the rest was
removed already) to check if the curl download expired, I took
the liberty to rename isValid to hasNotExpired.
This makes the class API a bit more sane, although
only a bit, because I had to leave it working with
possibly new code merged in from LL: the API can't
really change. I also removed some unused code.
While reviewing how LLFrameTimer worked however,
I did find a few instances where things where broken:
* sFrameDeltaTime wasn't correctly updated (more
than once per frame and therefore erratic). This
only influenced scrolling speed, but still.
* While dragging an inventory item, the scroll
arrows of a tab container didn't work
(LLTabContainer::handleDragAndDrop).
* Map zoom interpolation was broken (it interpolated
between A and B, but used the already updated
interpolation for A the next frame...
(added mCurZoomValInterpolationStart).
