Revision 1391501

Pivot-721: setFillIcon on ButtonDataRenderer has no effect.

Changed previous fix to put the set of "fill:true" only in the "setFillIcon"
method (because setting it always messed up the default behavior in a lot of
cases).

And, completely fixed the issue by setting the image preferred size to the
button size in the "fillIcon" case, which allows the image to completely
fill the button.

Also, fixed a copy/paste bug in the Pivot721.java test case.