[TASK] Add wmode param to YoutubeViewHelper

In IE10, IE11 the youtube player ignores its z-index.
You need to set this parameter to make the player behave like it’s
expected.

See
http://stackoverflow.com/questions/4050999/youtube-iframe-wmode-issue
for further details.

Classes/ViewHelpers/Media/YoutubeViewHelper.php

@@ -60,6 +60,7 @@ public function initializeArguments() {
 		$this->registerArgument('end', 'integer', 'Stop playing after seconds.', FALSE);
 		$this->registerArgument('lightTheme', 'boolean', 'Use the YouTube player\'s light theme.', FALSE, FALSE);
 		$this->registerArgument('videoQuality', 'string', 'Set the YouTube player\'s video quality (hd1080,hd720,highres,large,medium,small).', FALSE);
+		$this->registerArgument('wmode', 'string', 'Set the Window-Mode of the YouTube player (transparent,opaque). This is necessary for z-index handling in IE10/11.', FALSE);
 	}
 
 	/**
@@ -153,6 +154,9 @@ private function getSourceUrl($videoId) {
 		if (FALSE === empty($this->arguments['videoQuality'])) {
 			$params[] = 'vq=' . $this->arguments['videoQuality'];
 		}
+		if (FALSE === empty($this->arguments['wmode'])) {
+			$params[] = 'wmode=' . $this->arguments['wmode'];
+		}
 
 		if (FALSE === $this->arguments['legacyCode']) {
 			$src .= '/embed/'. $videoId;