Adding Node.insertAllBefore

tools/dom/templates/html/impl/impl_Node.darttemplate

Index: tools/dom/templates/html/impl/impl_Node.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Node.darttemplate b/tools/dom/templates/html/impl/impl_Node.darttemplate
index 307cd0cea96e329577874641d1b269bf174c973d..5782724089feb30d8cdbdcd2279f4bf499bf5660 100644
--- a/tools/dom/templates/html/impl/impl_Node.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Node.darttemplate
@@ -70,9 +70,10 @@ $endif
 
   void addAll(Iterable<Node> iterable) {
     if (iterable is _ChildNodeListLazy) {
-      if (iterable._this != _this) {
+      if (!identical(iterable._this, _this)) {
         // Optimized route for copying between nodes.
         for (var i = 0, len = iterable.length; i < len; ++i) {
+          // Should use $dom_firstChild, Bug 8886.
           _this.$dom_appendChild(iterable[0]);
         }
       }
@@ -291,5 +292,30 @@ $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
     return this;
   }
 
+  /**
+   * Inserts all of the nodes into this node directly before refChild.
+   *
+   * See also:
+   *
+   * * [insertBefore]
+   */
+  Node insertAllBefore(Iterable<Node> newNodes, Node refChild) {
+    if (newNodes is _ChildNodeListLazy) {
+      if (identical(newNodes._this, this)) {
+        throw new ArgumentError(newNodes);
+      }
+
+      // Optimized route for copying between nodes.
+      for (var i = 0, len = newNodes.length; i < len; ++i) {
+        // Should use $dom_firstChild, Bug 8886.
+        this.insertBefore(newNodes[0], refChild);
+      }
+    } else {
+      for (var node in newNodes) {
+        this.insertBefore(node, refChild);
+      }
+    }
+  }
+
 $!MEMBERS
 }