Fix integer overflow when stretch bitmap

When an image object is zoomed in by a big factor, the scaling factor in the transformation matrix is big as well, resulting in a large |dest_width| and |dest_height| value(they can be think of as the equivalent pixel size of the entire image, although most of it is outside the device).

BUG=395636
R=vitalybuka@chromium.org

Review URL: https://codereview.chromium.org/432543002