Making them GObjects is unnecessary. This enables further optimizations
down the road. The only place we use them in is gtkcssanimatedstyle.c
after all.
Because of our port of css animation and css transition to
progress tracker, we should not think of animated styles as
immutable objects that can map any timestamp to css values.
Rather, timestamps can correspond to different values depending
on the value of GTK_SLOWDOWN over the course of the animation.
To keep animated styles and style animations totally immutable,
we will not share styleanimations between animatedstyles, and
make a new copy of a styleanimation for each timestamp.
This adds the GtkCssAnimation class and the code needed to hook it into
GtkStyleContext. It takes the values out of the CSS "animation"
properties and does animations. See
http://dev.w3.org/csswg/css3-animations/
for details.
Note that the code for starting and stopping animations with widget
visibility doesn't work yet.
