fix(domFns): Fix "cannot read property 'call' of undefined"

Fixes #300, #303

lib/utils/domFns.js

@@ -19,8 +19,12 @@ export function matchesSelector(el: Node, selector: string): boolean {
     });
   }
 
+  // Might not be found entirely (not an Element?) - in that case, bail
   // $FlowIgnore: Doesn't think elements are indexable
-  return el[matchesSelectorFunc].call(el, selector);
+  if (!isFunction(el[matchesSelectorFunc])) return false;
+
+  // $FlowIgnore: Doesn't think elements are indexable
+  return el[matchesSelectorFunc](selector);
 }
 
 // Works up the tree to the draggable itself attempting to match selector.