Remove dead code

The MobileDiff page no longer exists, and was replaced with a redirect
that redirects to the desktop diff page, so this code can safely
be removed.

Bug: T360389
Change-Id: I8ebe2bc88a650caf29a5755013e980fe3b5aaeb0

src/RevisionSliderHooks.php

@@ -45,12 +45,6 @@ class RevisionSliderHooks implements DifferenceEngineViewHeaderHook, GetPreferen
 		$oldRevRecord = $differenceEngine->getOldRevision();
 		$newRevRecord = $differenceEngine->getNewRevision();
 
-		// do not show on MobileDiff page
-		// Note: Since T245172, DifferenceEngine::getTitle() is the title of the page being diffed.
-		if ( $differenceEngine->getOutput()->getTitle()->isSpecial( 'MobileDiff' ) ) {
-			return;
-		}
-
 		/**
 		 * If the user is logged in and has explictly requested to disable the extension don't load.
 		 */

tests/phpunit/RevisionSliderHooksTest.php

@@ -30,28 +30,6 @@ class RevisionSliderHooksTest extends \MediaWikiIntegrationTestCase {
 		$this->newInstance()->onDifferenceEngineViewHeader( $diffEngine );
 	}
 
-	public function testShouldNotLoadOnMobileDiff() {
-		// Arrange
-		$title = $this->createMock( Title::class );
-		$title->method( 'isSpecial' )
-			->with( 'MobileDiff' )
-			->willReturn( true );
-
-		$output = $this->createMock( OutputPage::class );
-		$output->method( 'getTitle' )
-			->willReturn( $title );
-
-		$revision = $this->createMock( RevisionRecord::class );
-		$diffEngine = $this->newDiffEngine( $revision, $output );
-
-		// Assert
-		$output->expects( $this->never() )
-			->method( 'addModules' );
-
-		// Act
-		$this->newInstance()->onDifferenceEngineViewHeader( $diffEngine );
-	}
-
 	public function testShouldNotLoadWhenUserIsLoggedInAndDisabledExtension() {
 		// Arrange
 		$options = [ 'revisionslider-disable' => true ];