update elements and fix some bugs

lib/firebase_collection.dart

 // DO NOT EDIT: auto-generated with `pub run custom_element_apigen:update`
 
 /// Dart API for the polymer element `firebase_collection`.
 @HtmlImport('firebase_collection_nodart.html')
 library polymer_elements.lib.src.firebase_element.firebase_collection;
 
 import 'dart:html';
 import 'dart:js' show JsArray, JsObject;
 import 'package:web_components/web_components.dart';
 import 'package:polymer_interop/polymer_interop.dart';
@@ skipping 109 matching lines @@
 
   /// Specify a start record for the set of records reflected in the
   /// collection.
   String get startAt => jsElement[r'startAt'];
   set startAt(String value) { jsElement[r'startAt'] = value; }
 
   /// Add an item to the document referenced at `location`. A key associated
   /// with the item will be created by Firebase, and can be accessed via the
   /// Firebase Query instance returned by this method.
   /// [data]: A value to add to the document.
-  add(data) =>
+  firebaseAdd(data) =>
       jsElement.callMethod('add', [data]);
 
   /// Look up an item in the local `data` Array by key.
   /// [key]: The key associated with the item in the parent
   ///     document.
   getByKey(String key) =>
       jsElement.callMethod('getByKey', [key]);
 
   /// Remove an item from the document referenced at `location`. The item
   /// is assumed to be an identical reference to an item already in the
   /// `data` Array.
   /// [data]: An identical reference to an item in `this.data`.
-  removeItem(data) =>
+  firebaseRemove(data) =>
       jsElement.callMethod('remove', [data]);
 
   /// Remove an item from the document associated with `location` by key.
   /// [key]: The key associated with the item in the document
   ///     located at `location`.
   removeByKey(String key) =>
       jsElement.callMethod('removeByKey', [key]);
 }