silence "layerX/Y" Webkit warnings for events

This means we can't just blindly extend all event properties onto the
event proxy object.

src/event.js

@@ -103,13 +103,17 @@
 
   var returnTrue = function(){return true},
       returnFalse = function(){return false},
+      ignoreProperties = /^([A-Z]|layer[XY]$)/,
       eventMethods = {
         preventDefault: 'isDefaultPrevented',
         stopImmediatePropagation: 'isImmediatePropagationStopped',
         stopPropagation: 'isPropagationStopped'
       }
   function createProxy(event) {
-    var proxy = $.extend({originalEvent: event}, event)
+    var key, proxy = { originalEvent: event }
+    for (key in event)
+      if (!ignoreProperties.test(key) && event[key] !== undefined) proxy[key] = event[key]
+
     $.each(eventMethods, function(name, predicate) {
       proxy[name] = function(){
         this[predicate] = returnTrue

test/event.html

@@ -129,6 +129,17 @@ <h1>Zepto event tests</h1>
         this.el.off({ click: fn }).off({ click: fn2 }, null)
         click(this.el)
         t.assertEqual('a b c c', log.sort().join(' '))
+      },
+
+      testDelegateEventProperties: function(t){
+        var type, target
+        $(document).on('click', 'div', function(e){
+          type = e.type
+          target = e.target
+        })
+        click(this.el)
+        t.assertEqual('click', type)
+        t.assertIdentical(this.el.get(0), target)
       }
     })
   })()