Removing dart:html APIs which were deprecated in M2.

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

Index: tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate b/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
index d9af15063eeb61fc6cec94ccd329fb7fe267afe6..c056cbaa79e4315e230bcbcac1a6f80a6e5c0ec0 100644
--- a/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
+++ b/tools/dom/templates/html/impl/impl_DocumentFragment.darttemplate
@@ -13,15 +13,6 @@ $(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
   factory $CLASSNAME.svg(String svgContent) =>
       _$(CLASSNAME)FactoryProvider.createDocumentFragment_svg(svgContent);
 
-  @deprecated
-  List<Element> get elements => this.children;
-
-  // TODO: The type of value should be Collection<Element>. See http://b/5392897
-  @deprecated
-  void set elements(value) {
-    this.children = value;
-  }
-
 $if DART2JS
   // Native field is used only by Dart code so does not lead to instantiation
   // of native classes