Adding docs to Element.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index a95a00e84402ca51651da4bbfd413eb84938e9fa..ca9576d2421f975fc3e5d2ce30d8756c12ee507d 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -9336,16 +9336,44 @@ class _ElementCssClassSet extends CssClassSet {
   }
 }
 
+/**
+ * The base class of all components for an HTML document.
+ */
 abstract class Element extends Node implements ElementTraversal {
 
+  /**
+   * Creates an HTML Element from a valid fragment of HTML.
+   * The [html] fragment must represent valid HTML with a single element root,
+   * which will be parsed and returned.
+   *
+   * Important: the contents of [html] should not contain any user-supplied
+   * data. Without strict data validation it is impossible to prevent script
+   * injection exploits.
+   *
+   * It is instead recommended that elements be constructed via [Element.tag]
+   * and text be added via [text].
+   */
   factory Element.html(String html) =>
       _ElementFactoryProvider.createElement_html(html);
+
+  /**
+   * Creates the HTML element specified by the tag name.
+   * This is similar to document.createElement.
+   * [tag] should be a valid HTML tag name. If [tag] is an unknown tag then
+   * this will create an [UnknownElement].
+   *     var element = new Element.tag('div');
+   * For standard elements it is more preferable to use the type constructors:
+   *     var element = new DivElement();
+   */
   factory Element.tag(String tag) =>
       _ElementFactoryProvider.createElement_tag(tag);
 
   /**
-   * @domName Element.hasAttribute, Element.getAttribute, Element.setAttribute,
-   *   Element.removeAttribute
+   * Provides access to all attributes on this element.
+   * This only includes attributes in the default namespace, additional
+   * attributes can be accessed via [getNamespacedAttributes].
+   * Any modifications to the map will automatically be applied to this
+   * element.
    */
   Map<String, String> get attributes => new _ElementAttributeMap(this);
 
@@ -9375,8 +9403,8 @@ abstract class Element extends Node implements ElementTraversal {
   List<Element> get elements => this.children;
 
   /**
-   * @domName childElementCount, firstElementChild, lastElementChild,
-   *   children, Node.nodes.add
+   * List of the direct children of this element.
+   * This collection can be used to add and remove elements from the document.
    */
   List<Element> get children => new _ChildrenElementList._wrap(this);
 
@@ -9388,12 +9416,32 @@ abstract class Element extends Node implements ElementTraversal {
     children.addAll(copy);
   }
 
+  /**
+   * Finds the first descendent element of this element that matches the
+   * specified group of selectors.
+   * [selectors] should be a string using CSS selector syntax.
+   *     var element = element.query('.className');
+   *     var element = element.query('#id');
+   */
   Element query(String selectors) => $dom_querySelector(selectors);
 
+  /**
+   * Finds all descendent elements of this element that match the specified
+   * group of selectors.
+   * [selectors] should be a string using CSS selector syntax.
+   *     var items = element.query('.itemClassName');
+   */
   List<Element> queryAll(String selectors) =>
     new _FrozenElementList._wrap($dom_querySelectorAll(selectors));
 
-  /** @domName className, classList */
+  /**
+   * The set of CSS classes applied to this element.
+   * This set makes it easy to add, remove or toggle the classes applied to
+   * this element.
+   *     element.classes.add('selected');
+   *     element.classes.toggle('isOnline');
+   *     element.classes.remove('selected');
+   */
   CssClassSet get classes => new _ElementCssClassSet(this);
 
   void set classes(Collection<String> value) {
@@ -9402,6 +9450,17 @@ abstract class Element extends Node implements ElementTraversal {
     classSet.addAll(value);
   }
 
+  /**
+   * Allows access to all custom data attributes (data-*) set on this element.
+   * The keys for the map must follow these rules:
+   * * The name must not begin with `xml`.
+   * * The name cannot contain a semi-colon (`;`).
+   * * The name cannot contain any capitol letters.
+   *
+   * Any keys from markup will be converted to camel-cased keys in the map
+   * This means that a key of 'camel-cased-name' would be converted to
+   * 'camelCasedName'.
+   */
   Map<String, String> get dataAttributes =>
     new _DataAttributeMap(attributes);
 
@@ -9421,13 +9480,23 @@ abstract class Element extends Node implements ElementTraversal {
     return new _NamespacedAttributeMap(this, namespace);
   }
 
-  /** @domName Window.getComputedStyle */
+  /**
+   * Gets the final set of all CSS values applied to this element, including
+   * inherited and default values.
+   * As opposed to the [style] property which contains the values specified
+   * directly on this element, computedStyle contains the values which are
+   * inherited from other sources, such as parent elements or stylesheets.
+   */
   Future<CSSStyleDeclaration> get computedStyle {
      // TODO(jacobr): last param should be null, see b/5045788
      return getComputedStyle('');
   }
 
-  /** @domName Window.getComputedStyle */
+  /**
+   * Gets the computed style of a pseudoElement of this element.
+   * Similar to [computedStyle] but this targets pseudo-elements such as
+   * `::after, ::before, ::marker, ::line-marker`.
+   */
   Future<CSSStyleDeclaration> getComputedStyle(String pseudoElement) {
     return _createMeasurementFuture(
         () => window.$dom_getComputedStyle(this, pseudoElement),