Bug 826817. Part 1: Send WillPaintWindow/DidPaintWindow from all widget implementations. r=tnikkel
Bug 826817. Part 2: Remove will-send-did-paint and did-send-will-paint flags from nsIWidgetListener::PaintWindow. r=tnikkel
Bug 826817. Part 3: Remove will-send-did-paint flag from nsIWidgetListener::WillPaintWindow. r=tnikkel
Bug 826817. Part 4: Remove will-send-did-paint and did-send-will-paint flags from nsIPresShell APIs. r=tnikkel