Drive drawProjectionFrame with a fake runtime and a recording canvas:
a 640x480 still draws at its fitted rectangle over the matte, the same
pixels at the same size skip the redraw, and the same pixels at a new
aspect redraw at the new fit. The last case fails on the pixel-only
signature; the first fails if drawImage stretches to the canvas again.
Expected rectangles now read the canvas size from policy.js.
Co-Authored-By: Claude Opus 5.5 <[email protected]>
