resourceloader: Remove internal 'sync' option from ClientHtml

This only existed for Special:JavaScriptTest, which no longer
uses it as of I739850483.

Change-Id: If60def1a53707d31adf897b10baed109ebb6b8f0

includes/resourceloader/ResourceLoaderClientHtml.php

@@ -468,10 +468,8 @@ JAVASCRIPT;
 							// Use cases:
 							// - startup (naturally because this is what will define mw.loader)
 							// - html5shiv (loads synchronously in old IE before the async startup module arrives)
-							// - QUnit (needed in SpecialJavaScriptTest before async startup)
 							$chunk = Html::element( 'script', [
-								// The 'sync' option is only supported in combination with 'raw'.
-								'async' => !isset( $extraQuery['sync'] ),
+								'async' => true,
 								'src' => $url
 							] );
 						} else {

tests/phpunit/includes/resourceloader/ResourceLoaderClientHtmlTest.php

@@ -230,13 +230,6 @@ Deprecation message.' ]
 				'extra' => [ 'raw' => '1' ],
 				'output' => '<script async="" src="/w/load.php?lang=nl&amp;modules=test.scripts&amp;only=scripts&amp;raw=1"></script>',
 			],
-			[
-				'context' => [],
-				'modules' => [ 'test.scripts' ],
-				'only' => ResourceLoaderModule::TYPE_SCRIPTS,
-				'extra' => [ 'raw' => '1', 'sync' => '1' ],
-				'output' => '<script src="/w/load.php?lang=nl&amp;modules=test.scripts&amp;only=scripts&amp;raw=1&amp;sync=1"></script>',
-			],
 			[
 				'context' => [],
 				'modules' => [ 'test.scripts.user' ],