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 3f7757118294bd61bad18f0df57f535dc5400d6d..c8a56f371115dbdb072eaca81e9a3e81dab03767 100644
--- a/tools/dom/templates/html/impl/impl_Element.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Element.darttemplate
@@ -769,6 +769,49 @@ $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({bool alignCenter, bool alignTop, bool alignBottom}) {

[Jacob, 2013/02/12 23:12:33]

shouldn't this be an enum instead of 3 bools?

+    var paramCount = (alignCenter != null ? 1 : 0) +
+        (alignTop != null ? 1 : 0) + (alignBottom != null ? 1 : 0);
+    if (paramCount > 1) {
+      throw new ArgumentError(
+          'Can only specify one of alignCenter, alignTop, alignBottom');
+    }
+    var scrollIntoViewIfNeeded = false;
+$if DART2JS
+    scrollIntoViewIfNeeded = JS('bool', '!!(#.scrollIntoViewIfNeeded)', this);
+$endif
+    if (alignTop != null) {
+      this.$dom_scrollIntoView(alignTop);
+    } else if (alignBottom != null) {
+      this.$dom_scrollIntoView(alignBottom);
+    } else if (scrollIntoViewIfNeeded) {
+      if (alignCenter != null) {
+        this.$dom_scrollIntoViewIfNeeded(alignCenter);
+      } else {
+        this.$dom_scrollIntoViewIfNeeded();
+      }
+    } else {
+      this.$dom_scrollIntoView();
+    }
+  }
+
 $if DART2JS
   @DomName('Element.mouseWheelEvent')
   static const EventStreamProvider<WheelEvent> mouseWheelEvent =