* Add a test-only setter to the center-item XBL binding
* add a head.js function to remove plugin permissions for use in cleanup functions
* browser_pluginnotification.js - lots of fixes for the core feature tests
* Alter test_bug751809 not to assume that clicking the page overlay will directly activate the plugin
* Alter browser_CTP_plugins.js because disabled plugins now do show up in the plugin doorhanger
* remove browser_CTPScriptPlugin.js and supporting files because we no longer auto-pop based on scripting
* fix browser_CTP_drag_drop.js so that active plugins still show the doorhanger icon, and other fixup
* fix browser_bug743421.js to expect the doorhanger all the time and activate it correctly
* fix browser_bug752516.js to check for doorhanger activation instead of plugin activation
* remove browser_bug818009.js and supporting files because they are testing something that no longer exists
* alter browser_bug820497.js so that it shows the popup notification before checking .centerActions, since we populate that data lazily now
* browser_plugins_added_dynamically.js: remove the "activate all" tests which are no longer relevant and fix the rest to match the new doorhanger structure.
