Change size, opacity and zoom event Listeners to 'change'.
Change size, opacity and zoom event Listeners to 'change'.

Allows them to be controlled using the keyboard arrow keys.

R=calamity@chromium.org, jackhou@chromium.org

Review URL: https://codereview.appspot.com/50160044

jackhou-chromium/bitmapper,jackhou-chromium/bitmapper,jackhou-chromium/bitmapper