Extract the element implementation logic to function mods in <webview>.
function mods end with "$".
"element" inside <webview> is currently the plugin <object> element, i.e.
the browser plugin. This CL makes it possible to provide a different
implementation for the element. This CL also provides a stub
using <iframe>. This will be used by the <webview> using OOPIF
architecture CL: https://chromiumcodereview.appspot.com/972313002/
BUG=330264
Test=None, no visible changes.
Review URL: https://codereview.chromium.org/1165773004
Cr-Commit-Position: refs/heads/master@{#333592}
14 files changed
