Update the annotationLayer when using CSS only zoom

Currently when using CSS only zoom, the annotationLayer will not be updated. This causes links, and other annotations, to appear in the wrong positions when the document is zoomed.

To see this issue in action, open: http://arxiv.org/pdf/1112.0542v1.pdf#useOnlyCssZoom=true; and the zoom the document. Note how the position of the links isn't updated.

This patch thus fixes an issue that regressed in #3727.