Factory interface to generate properties for all animated targets.
Depending on mode and content of a SMIL animation tree, animation
targets can have global properties different from the target's
default. The most prominent example for such a difference is shape
visibility: when a shape is to become visible in the course of a
SMIL animation, it naturally has to be initially invisible for
that effect to have any visible impact.
This factory interface is able to generate sequences of global
properties for all targets referenced in a given SMIL animation
tree.
This method generates a sequence of TargetProperties in effect
before the given SMIL animations start. These properties
should be applied to the given animation targets, to achieve
correct playback of the SMIL animations.
