Addition: Name from heading

closes #457

Related to the following:
- w3c/aria#1860
- w3c/accname#229 (this needs to be merged so the new links to 'accName: name from heading' will work

index.html

@@ -16435,6 +16435,26 @@ <h4>Other Form Elements Accessible Name Computation</h4>
           </li>
         </ol>
       </section>
+      <section>
+        <h4>`dialog` Element Accessible Name Computation</h4>
+        <ol>
+          <li>
+            If the `dialog` element has an <a data-cite="wai-aria-1.2/#aria-label">`aria-label`</a> or an 
+            <a data-cite="wai-aria-1.2/#aria-labelledby">`aria-labelledby`</a> attribute the 
+            <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is to be calculated using the algorithm defined in 
+            <a class="accname">Accessible Name and Description: Computation and API Mappings</a>.
+          </li>
+          <li>
+            If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then: if the `dialog` element has a 
+            <a href="https://dom.spec.whatwg.org/#concept-tree-descendant">descendant</a> that is a heading element (`h1`-`h6`), then use the subtree of the first such element
+            as defined in <a data-cite="accname-1.2/#comp_name_from_heading">accname: Name from Heading</a>.
+          </li>
+          <li>
+            If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then:, if the `dialog` element has a `title` attribute, then use that attribute.
+          </li>
+          <li>Otherwise, there is no <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.</li>
+        </ol>
+      </section>
       <section>
         <h4>`summary` Element Accessible Name Computation</h4>
         <ol>
@@ -16451,6 +16471,26 @@ <h4>`summary` Element Accessible Name Computation</h4>
           </li>
         </ol>
       </section>
+      <section>
+        <h4>`article` Element Accessible Name Computation</h4>
+        <ol>
+          <li>
+            If the `article` element has an <a data-cite="wai-aria-1.2/#aria-label">`aria-label`</a> or an 
+            <a data-cite="wai-aria-1.2/#aria-labelledby">`aria-labelledby`</a> attribute the 
+            <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is to be calculated using the algorithm defined in 
+            <a class="accname">Accessible Name and Description: Computation and API Mappings</a>.
+          </li>
+          <li>
+            If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then: if the `article` element has a 
+            <a href="https://dom.spec.whatwg.org/#concept-tree-descendant">descendant</a> that is a heading element (`h1`-`h6`), then use the subtree of the first such element
+            as defined in <a data-cite="accname-1.2/#comp_name_from_heading">accname: Name from Heading</a>.
+          </li>
+          <li>
+            If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then:, if the `article` element has a `title` attribute, then use that attribute.
+          </li>
+          <li>Otherwise, there is no <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.</li>
+        </ol>
+      </section>
       <section>
         <h4>`figure` Element Accessible Name Computation</h4>
         <ol>
@@ -16547,7 +16587,7 @@ <h4>`iframe` Element Accessible Name Computation</h4>
         <p class="note">The document referenced by the `src` of the `iframe` element gets its name from that document's `title` element, like any other document. If there is no `title` provided, there is no accessible name.</p>
       </section>
       <section>
-        <h4>Section and Grouping Element Accessible Name Computation</h4>
+        <h4>Other Section and Grouping Element Accessible Name Computation</h4>
         <ol>
           <li>
             If the element  has an <a data-cite="wai-aria-1.2/#aria-label">`aria-label`</a> or an <a data-cite="wai-aria-1.2/#aria-labelledby">`aria-labelledby`</a> attribute the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is to be calculated using the algorithm defined in <a href="" class="accname">Accessible Name and Description: Computation and API Mappings</a>.