Support custom ScrollView implementations in ListView

Summary: See e9f64b2#commitcomment-16166567

Reviewed By: tadeuzagallo

Differential Revision: D2953787

fb-gh-sync-id: b8978b3fa6ae9e848be918cc707335a06ea56cf6
shipit-source-id: b8978b3fa6ae9e848be918cc707335a06ea56cf6

Libraries/CustomComponents/ListView/ListView.js

@@ -231,14 +231,18 @@ var ListView = React.createClass({
 
   /**
    * Provides a handle to the underlying scroll responder.
+   * Note that the view in `SCROLLVIEW_REF` may not be a `ScrollView`, so we
+   * need to check that it responds to `getScrollResponder` before calling it.
    */
   getScrollResponder: function() {
-    return this.refs[SCROLLVIEW_REF] && 
+    return this.refs[SCROLLVIEW_REF] &&
+      this.refs[SCROLLVIEW_REF].getScrollResponder &&
       this.refs[SCROLLVIEW_REF].getScrollResponder();
   },
 
   scrollTo: function(...args) {
-    this.refs[SCROLLVIEW_REF] && 
+    this.refs[SCROLLVIEW_REF] &&
+      this.refs[SCROLLVIEW_REF].scrollTo &&
       this.refs[SCROLLVIEW_REF].scrollTo(...args);
   },