Revert "implement RAIIEventEmitter.discard and free generic listeners"

This reverts commit 345d045.

Author: whoozle

core/RAIIEventEmitter.qml

@@ -5,14 +5,6 @@ EventEmitter {
 		this._onListener = {}
 	}
 
-	function discard() {
-		var listeners = this._onListener
-		for(var name in listeners) {
-			this.removeAllListeners(name)
-		}
-		$core.EventEmitter.prototype.discard.call(this)
-	}
-
 	///@private
 	function on (name, callback) {
 		if (!(name in this._eventHandlers)) {