Updating Element.scrollIntoView to be platform independent.

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of $LIBRARYNAME;
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
 class _ChildrenElementList implements List {
   // Raw Element.
@@ skipping 757 matching lines @@
    * deprecated and will simply return this [Element] object.
    *
    * [wc]: http://dvcs.w3.org/hg/webcomponents/raw-file/tip/explainer/index.html
    * [x-tags]: http://x-tags.org/
    */
 $if DART2JS
   @Creates('Null')  // Set from Dart code; does not instantiate a native type.
 $endif
   var xtag;
 
+  /**
+   * Scrolls this element into view.
+   *
+   * Only one of of the alignment options may be specified at a time.
+   *
+   * If no options are specified then this will attempt to scroll the minimum
+   * amount needed to bring the element into view.
+   *
+   * Note that alignCenter is currently only supported on WebKit platforms. If
+   * alignCenter is specified but not supported then this will fall back to
+   * alignTop.
+   *
+   * See also:
+   *
+   * * [scrollIntoView](http://docs.webplatform.org/wiki/dom/methods/scrollIntoView)
+   * * [scrollIntoViewIfNeeded](http://docs.webplatform.org/wiki/dom/methods/scrollIntoViewIfNeeded)
+   */
+  void scrollIntoView([ScrollIntoViewAlignment alignment]) {
+    var hasScrollIntoViewIfNeeded = false;
+$if DART2JS
+    hasScrollIntoViewIfNeeded =
+        JS('bool', '!!(#.scrollIntoViewIfNeeded)', this);
+$endif
+    if (alignment == ScrollIntoViewAlignment.TOP) {
+      this.$dom_scrollIntoView(true);
+    } else if (alignment == ScrollIntoViewAlignment.BOTTOM) {
+      this.$dom_scrollIntoView(false);
+    } else if (hasScrollIntoViewIfNeeded) {
+      if (alignment == ScrollIntoViewAlignment.CENTER) {
+        this.$dom_scrollIntoViewIfNeeded(true);
+      } else {
+        this.$dom_scrollIntoViewIfNeeded();
+      }
+    } else {
+      this.$dom_scrollIntoView();
+    }
+  }
+
 $if DART2JS
   @DomName('Element.mouseWheelEvent')
   static const EventStreamProvider<WheelEvent> mouseWheelEvent =
       const _CustomEventStreamProvider<WheelEvent>(
         Element._determineMouseWheelEventType);
 
   static String _determineMouseWheelEventType(EventTarget e) {
     if (JS('bool', '#.onwheel !== undefined', e)) {
       // W3C spec, and should be IE9+, but IE has a bug exposing onwheel.
       return 'wheel';
@@ skipping 269 matching lines @@
   // Optimization to improve performance until the dart2js compiler inlines this
   // method.
   static dynamic createElement_tag(String tag) =>
       // Firefox may return a JS function for some types (Embed, Object).
       JS('Element|=Object', 'document.createElement(#)', tag);
 $else
   static Element createElement_tag(String tag) =>
       document.$dom_createElement(tag);
 $endif
 }
+
+
+/**
+ * Options for Element.scrollIntoView.
+ */
+class ScrollIntoViewAlignment {
+  final _value;
+  const ScrollIntoViewAlignment._internal(this._value);
+  toString() => 'ScrollIntoViewAlignment.$_value';
+
+  /// Attempt to align the element to the top of the scrollable area.
+  static const TOP = const ScrollIntoViewAlignment._internal('TOP');
+  /// Attempt to center the element in the scrollable area.
+  static const CENTER = const ScrollIntoViewAlignment._internal('CENTER');
+  /// Attempt to align the element to the bottom of the scrollable area.
+  static const BOTTOM = const ScrollIntoViewAlignment._internal('BOTTOM');
+}