Updating Element.scrollIntoView to be platform independent.

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

Index: tools/dom/templates/html/impl/impl_Element.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Element.darttemplate b/tools/dom/templates/html/impl/impl_Element.darttemplate
index 47f53c1499bb9d69bbeef8a90b6b01a4730e170c..6eaee82e28648711977bdda3f7c4155931a2f858 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -775,6 +775,44 @@ $if DART2JS
 $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 =
@@ -1064,3 +1102,20 @@ $else
       document.$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');
+}