Menu and Tree Patterns: Remove parent node labeling guidance

Per issue #395, made the following deletions from the menu and tree patterns.

Removed following from menu pattern:

> A parent menuitem has either aria-label or aria-labelledby set to specify a label.
> Warning: parent menuitems missing a label are labeled by all child elements,
> causing screen readers to announce every child menuitem and often making a menu so verbose that it is unusable.

Removed the following from the treeview pattern:

> Each element with role treeitem that serves as a parent node has either aria-label r aria-labelledby set to specify a label.
> Warning: parent nodes missing a label are labeled by all child elements,
> causing screen readers to announce every child and often making a tree so verbose that it is unusable.

aria-practices.html

@@ -1505,12 +1505,6 @@ <h4>WAI-ARIA Roles, States, and Properties</h4>
           <li>
             If activating a <a href="#menuitem" class="role-reference">menuitem</a> opens a submenu, the menuitem is known as a parent menuitem.
             A submenu's <code>menu</code> element is contained in or owned by it's parent             menuitem.
-          <li>
-          A parent menuitem has either
-            <a class="property-reference" href="#aria-label">aria-label</a> or <a class="property-reference" href="#aria-labelledby">aria-labelledby</a>
-            set to specify a label.
-            Warning: parent menuitems missing a label are labeled by             all child elements,
-            causing screen readers to announce every child menuitem and often making a menu so verbose that it is unusable.
           </li>
           <li>A parent menuitem has <a href="#aria-haspopup" class="property-reference">aria-haspopup</a> set to <code>true</code>. </li>
           <li>One of the following approaches is used to enable scripts to move focus among items in a menu as described in <a href="#kbd_general_within"></a>:
@@ -2266,13 +2260,6 @@ <h4>WAI-ARIA Roles, States, and Properties</h4>
             set to <code>false</code> when the node is in a closed state and set to <code>true</code> when the node is in an open state.
             End nodes do not have the <code>aria-expanded</code> attribute because, if they were to have it, they would be incorrectly described to assistive technologies as parent nodes.
           </li>
-          <li>
-            Each element with role <code>treeitem</code> that serves as a parent node has either
-            <a class="property-reference" href="#aria-label">aria-label</a> or <a class="property-reference" href="#aria-labelledby">aria-labelledby</a>
-            set to specify a label.
-            Warning: parent nodes missing a label are labeled by             all child elements,
-            causing screen readers to announce every child and often making a tree so verbose that it is unusable.
-          </li>
           <li>If the tree supports selection of more than one node, the element with role <code>tree</code> has <a class="property-reference" href="#aria-multiselectable">aria-multiselectable</a> set to <code>true</code>. Otherwise, <code>aria-multiselectable</code> is either set to <code>false</code> or the default value of <code>false</code> is implied.</li>
           <li>If the tree does not support multiple selection, <a href="#aria-selected" class="property-reference">aria-selected</a> is set to <code>true</code> for the selected node and it is not present on any other node in the tree.</li>
           <li>if the tree supports multiple selection: