Revert "Implementing polyfills for insertAdjacent* to get them working on FF."

lib/dom/templates/html/interface/interface_Element.darttemplate

Index: lib/dom/templates/html/interface/interface_Element.darttemplate
diff --git a/lib/dom/templates/html/interface/interface_Element.darttemplate b/lib/dom/templates/html/interface/interface_Element.darttemplate
index 2567513210f55a00ca74ffa5371b812aaaae1346..455eb0d24f804990c5402ad2773a97dca3bd0125 100644
--- a/lib/dom/templates/html/interface/interface_Element.darttemplate
+++ b/lib/dom/templates/html/interface/interface_Element.darttemplate
@@ -72,17 +72,6 @@ interface Element extends Node, NodeSelector default _$(ID)FactoryProvider {
   void set dataAttributes(Map<String, String> value);
 
   /**
-   * Adds the specified text as a text node after the last child of this.
-   */
-  void addText(String text);
-
-  /**
-   * Parses the specified text as HTML and adds the resulting node after the
-   * last child of this.
-   */
-  void addHTML(String html);
-
-  /**
    * @domName getClientRects, getBoundingClientRect, clientHeight, clientWidth,
    * clientTop, clientLeft, offsetHeight, offsetWidth, offsetTop, offsetLeft,
    * scrollHeight, scrollWidth, scrollTop, scrollLeft