While reviewing an unrelated change I discovered an incompatible API change (although a fairly minor one) that appears to be a side effect from RT-35175.

 class javafx/scene/control/PopupControl$CSSBridge contains the following method in FX 8:
   public javafx.css.Styleable getStyleableParent();

That method was made final as part of RT-35175. This has the potential to break both source and binary compatibility, if anyone were to subclass PopupControl.CSSBridge (this seems unlikely).