fix(zepto): catch exceptions while assigning (#298)

Author: briganti

zepto.js

@@ -1077,7 +1077,9 @@
         event[predicate] = returnFalse
       })
 
-      event.timeStamp || (event.timeStamp = Date.now())
+      try {
+        event.timeStamp || (event.timeStamp = Date.now())
+      } catch (ignored) { }
 
       if (source.defaultPrevented !== undefined ? source.defaultPrevented :
           'returnValue' in source ? source.returnValue === false :