resourceloader: Set the request base parameters on server-side

This change also removes the defaults from the URL parameter:
* lang=qqx
* skin=fallback
* debug=false

Bug: T225899
Change-Id: I4cbc42e39ebc56c3d29f773a275afe2b1a44c913

includes/resourceloader/ResourceLoaderContext.php

@@ -410,4 +410,24 @@ class ResourceLoaderContext implements MessageLocalizer {
 		}
 		return $this->hash;
 	}
+
+	/**
+	 * Get the request base parameters, omitting any defaults.
+	 *
+	 * @internal For internal use by ResourceLoaderStartUpModule only
+	 * @return array
+	 */
+	public function getReqBase() {
+		$reqBase = [];
+		if ( $this->getLanguage() !== self::DEFAULT_LANG ) {
+			$reqBase['lang'] = $this->getLanguage();
+		}
+		if ( $this->getSkin() !== self::DEFAULT_SKIN ) {
+			$reqBase['skin'] = $this->getSkin();
+		}
+		if ( $this->getDebug() ) {
+			$reqBase['debug'] = 'true';
+		}
+		return $reqBase;
+	}
 }

includes/resourceloader/ResourceLoaderStartUpModule.php

@@ -401,6 +401,7 @@ class ResourceLoaderStartUpModule extends ResourceLoaderModule {
 
 		// Perform replacements for mediawiki.js
 		$mwLoaderPairs = [
+			'$VARS.reqBase' => ResourceLoader::encodeJsonForScript( $context->getReqBase() ),
 			'$VARS.baseModules' => ResourceLoader::encodeJsonForScript( $this->getBaseModules() ),
 			'$VARS.maxQueryLength' => ResourceLoader::encodeJsonForScript(
 				$conf->get( 'ResourceLoaderMaxQueryLength' )

resources/src/startup/mediawiki.js

@@ -1606,11 +1606,7 @@
 				batch.sort();
 
 				// Query parameters common to all requests
-				reqBase = {
-					skin: mw.config.get( 'skin' ),
-					lang: mw.config.get( 'wgUserLanguage' ),
-					debug: mw.config.get( 'debug' )
-				};
+				reqBase = $VARS.reqBase;
 
 				// Split module list by source and by group.
 				splits = Object.create( null );