The Extend Bounds input has no effect when the Fast Gaussian filter is
used. Similarly, it has no effect if the Bokeh Blur node is using
variable size. This is a known limitation and was just not implemented.
So to fix this, we implement a general solution that works globally
across the node by pre-padding the inputs of the blur. This uses more
memory but also speeds up the base case when Extend Bounds is disabled,
while also reducing the binary size due to fewer blur specializations.
The variable size Bokeh Blur test was updated since it Extend Bounds was
silently ignored.
Pull Request: https://projects.blender.org/blender/blender/pulls/140192
9bcb536c95