First pass at ARIA. Video player buttons announce themselves as button when used with a screen reader

common/lib/xmodule/xmodule/js/src/video/04_video_control.js

@@ -63,6 +63,10 @@ function () {
             state.videoControl.el.addClass('html5');
             state.controlHideTimeout = setTimeout(state.videoControl.hideControls, state.videoControl.fadeOutTimeout);
         }
+        // ARIA
+        // Let screen readers know these anchors behaves like a button.
+        state.videoControl.playPauseEl.attr('role', gettext('button'));
+        state.videoControl.fullScreenEl.attr('role', gettext('button'));
     }
 
     // function _bindHandlers(state)

common/lib/xmodule/xmodule/js/src/video/05_video_quality_control.js

@@ -43,6 +43,9 @@ function () {
 
         state.videoQualityControl.el.show();
         state.videoQualityControl.quality = null;
+        // ARIA
+        // Let screen readers know this anchor behaves like a button.
+        state.videoQualityControl.el.attr('role', gettext('button'));
     }
 
     // function _bindHandlers(state)

common/lib/xmodule/xmodule/js/src/video/07_video_volume_control.js

@@ -62,6 +62,9 @@ function () {
         });
 
         state.videoVolumeControl.el.toggleClass('muted', state.videoVolumeControl.currentVolume === 0);
+        // ARIA
+        // Let screen readers know this anchor behaves like a button.
+        state.videoVolumeControl.buttonEl.attr('role', gettext('button'));
     }
 
     /**

common/lib/xmodule/xmodule/js/src/video/08_video_speed_control.js

@@ -79,6 +79,9 @@ function () {
         });
 
         state.videoSpeedControl.setSpeed(state.speed);
+        // ARIA
+        // Let screen readers know this anchor behaves like a button.
+        state.videoSpeedControl.el.children('a').attr('role', gettext('button'));
     }
 
     /**

common/lib/xmodule/xmodule/js/src/video/09_video_caption.js

@@ -105,6 +105,9 @@ function () {
             this.videoCaption.hideCaptions(true);
             this.videoCaption.hideSubtitlesEl.hide();
         }
+        // ARIA
+        // Let screen readers know this anchor behaves like a button.
+        this.videoCaption.hideSubtitlesEl.attr('role', gettext('button'));
     }
 
     // function bindHandlers()