Added a notion of "background color" to LLViewerMediaImpl and LLPluginClassMedia.
Added background color parameters to the size_change message.
Webkit plugin now sets the background color of the instance from the supplied background color, and navigates to a data: url with that background color instead of about:blank as its initial navigate.
Webkit plugin now no longer waits for the first onPageChanged event
LLViewerMediaImpl now clears the texture to the background color when initializing it.
Made LLMediaCtrl fill with its opaque background color when the media impl isn't set up yet.
Removed the initial data URL from the search and help floaters, since what it was doing is now handled internally by the new background color code.
Reviewed by callum and rick.
3b2697cb93