Add option to disable CodeMirror frontend

So CodeMirror only provides it's libraries to use in other code.

Change-Id: I6832f4d82ae0497b92ba210ac7960052e4e12143

CodeMirror.hooks.php

@@ -66,10 +66,13 @@ class CodeMirrorHooks {
 	 * @return boolean
 	 */
 	private static function isCodeMirrorEnabled( IContextSource $context ) {
+		global $wgCodeMirrorEnableFrontend;
+
 		// Check, if we already checked, if page action is editing, if not, do it now
 		if ( is_null( self::$isEnabled ) ) {
 			// edit can be 'edit' and 'submit'
-			self::$isEnabled = in_array(
+			self::$isEnabled = $wgCodeMirrorEnableFrontend &&
+				in_array(
 					Action::getActionName( $context ),
 					array( 'edit', 'submit' )
 				);
@@ -176,10 +179,12 @@ class CodeMirrorHooks {
 	 * @return bool Always true
 	 */
 	public static function onGetPreferences( User $user, &$defaultPreferences ) {
+		if ( self::isCodeMirrorEnabled( RequestContext::getMain() ) ) {
 			$defaultPreferences['usecodemirror'] = array(
 				'type' => 'api',
 				'default' => '1',
 			);
+		}
 		return true;
 	}
 }

CodeMirror.php

@@ -71,3 +71,11 @@ $wgResourceModules['ext.CodeMirror.lib'] = $wgCodeMirrorResourceTemplate + array
 	'group' => 'ext.CodeMirror',
 	'targets' => array( 'mobile', 'desktop' ),
 );
+
+// Configuration options
+
+/**
+ * Specify, if CodeMirror extension should integrate CodeMirror in MediaWiki's editor (or WikiEditor), or if
+ * it should work as a library provider for other extensions.
+ */
+$wgCodeMirrorEnableFrontend = true;