Remove the activation behavior of media elements

This came about at the end of a long thread about click events:
https://lists.w3.org/Archives/Public/public-whatwg-archive/2013Nov/0344.html

I have abandoned the effort to implement this in Blink, as it turns
out that we don't really want clicks anywhere to play/pause:
https://code.google.com/p/chromium/issues/detail?id=354746#c18

This reverts most of the following:
 * commit fe3fa17 (r8315)
 * commit 9e32c95 (r8766)
 * commit 8cbd162 (r8767)

source

@@ -33365,13 +33365,6 @@ interface <dfn>MediaController</dfn> : <span>EventTarget</span> {
 
   </ol>
 
-  <p>A <code>MediaController</code> is a <dfn>restrained media controller</dfn> if the
-  <code>MediaController</code> is a <span>playing media controller</span>, but either at least one
-  of its <span>slaved media elements</span> whose <span>autoplaying flag</span> is true still has
-  its <code data-x="dom-media-paused">paused</code> attribute set to true, or, all of its
-  <span>slaved media elements</span> have their <code data-x="dom-media-paused">paused</code>
-  attribute set to true.</p>
-
   <p>A <code>MediaController</code> is a <dfn>blocked media controller</dfn> if the
   <code>MediaController</code> is a <span>paused media controller</span>, or if any of its
   <span>slaved media elements</span> are <span data-x="blocked media element">blocked media
@@ -35562,43 +35555,6 @@ red:89
   element</span> without affecting the <code>MediaController</code>, but such features are
   considered relatively advanced and unlikely to be useful to most users.</p>
 
-  <p>The <span>activation behaviour</span> of a <span>media element</span> that is <span
-  data-x="expose a user interface to the user">exposing a user interface to the user</span> must be
-  to run the following steps:</p>
-
-  <ol>
-
-   <li><p>If the <span>media element</span> has a <span>current media controller</span>, and that
-   <span>current media controller</span> is a <span>restrained media controller</span>, then invoke
-   the <code data-x="dom-MediaController-play">play()</code> method of the
-   <code>MediaController</code> and abort these steps.</p></li>
-
-   <li><p>If the <span>media element</span> has a <span>current media controller</span>,
-   and that <span>current media controller</span> is a <span>paused media controller</span>, all
-   of the <code>MediaController</code>'s <span>slaved media elements</span> have <span>ended
-   playback</span>, and the <span>media controller playback rate</span> is positive or zero, then
-   <span>seek the media controller</span> to zero.</p></li>
-
-   <li><p>If the <span>media element</span> has a <span>current media controller</span>,
-   and that <span>current media controller</span> is a <span>paused media controller</span>, then
-   invoke the <code data-x="dom-MediaController-unpause">unpause()</code> method of the
-   <code>MediaController</code> and abort these steps.</p></li>
-
-   <li><p>If the <span>media element</span> has a <span>current media controller</span>,
-   then that <span>current media controller</span> is a <span>playing media controller</span>;
-   invoke the <code data-x="dom-MediaController-pause">pause()</code> method of the
-   <code>MediaController</code> and abort these steps.</p></li>
-
-   <li><p>If
-   the <span>media element</span>'s <code data-x="dom-media-paused">paused</code> attribute is true,
-   then invoke the <code data-x="dom-media-play">play()</code> method on the <span>media
-   element</span> and abort these steps.</p></li>
-
-   <li><p>Invoke the <code data-x="dom-media-pause">pause()</code> method on the <span>media
-   element</span>.</p></li>
-
-  </ol>
-
   <p>For the purposes of listing chapters in the <span>media resource</span>, only <span data-x="text
   track">text tracks</span> in the <span>media element</span>'s <span>list of text tracks</span>
   that are <span data-x="text track showing">showing</span> and whose <span>text track kind</span> is