Remove function wrappers in DOMSelection

There is no point in doing the feature detection on every call, unless there is an IE bug where it is not sure about which support for selection it has (totally plausible).

src/browser/ui/ReactDOMSelection.js

@@ -171,19 +171,13 @@ var ReactDOMSelection = {
   /**
    * @param {DOMElement} node
    */
-  getOffsets: function(node) {
-    var getOffsets = document.selection ? getIEOffsets : getModernOffsets;
-    return getOffsets(node);
-  },
+  getOffsets: document.selection ? getIEOffsets : getModernOffsets,
 
   /**
    * @param {DOMElement|DOMTextNode} node
    * @param {object} offsets
    */
-  setOffsets: function(node, offsets) {
-    var setOffsets = document.selection ? setIEOffsets : setModernOffsets;
-    setOffsets(node, offsets);
-  }
+  setOffsets: document.selection ? setIEOffsets : setModernOffsets
 };
 
 module.exports = ReactDOMSelection;