Updating Element.scrollIntoView to be platform independent.

tests/html/element_test.dart

Index: tests/html/element_test.dart
diff --git a/tests/html/element_test.dart b/tests/html/element_test.dart
index 981db6d26224e4c4a49c65aa1abcf40270f5ced1..3acf33c01c2a3ff97026f18ffe1687dabaeb802d 100644
--- a/tests/html/element_test.dart
+++ b/tests/html/element_test.dart
@@ -618,6 +618,18 @@ main() {
     testUnsupported('removeLast', () => getQueryAll().removeLast());
   });
 
+  group('functional', () {
+    test('scrollIntoView', () {
+      var child = new DivElement();
+      document.body.append(child);
+
+      child.scrollIntoView(ScrollIntoViewAlignment.TOP);
+      child.scrollIntoView(ScrollIntoViewAlignment.BOTTOM);
+      child.scrollIntoView(ScrollIntoViewAlignment.CENTER);
+      child.scrollIntoView();
+    });
+  });
+
   group('_ElementList', () {
     List<Element> makeElList() => makeElementWithChildren().children;