SkinMinerva testGetContextSpecificModule test might use undefined title

Test scenario for getContextSpecificModules() mocks only Skin->getTitle()
behavior, but while executing isAllowedPageAction() Skin will create a
UserPageHelper with default RequestContext. As RequestContext is not mocked,
$context->getTitle() will return undefined what could lead to tests crash

Changes:
 - instead of mocking SkinMinerva::getTitle() pass test context with injected
title. Other tests will work properly as MediaWikiTestCase::tearDown() always
restes RequestContext to default

Bug: T170624
Change-Id: I872fddf8d9c52a6875bb6c69a12407a8125fba4c

tests/phpunit/skins/SkinMinervaTest.php

@@ -177,10 +177,10 @@ class SkinMinervaTest extends MediaWikiTestCase {
 				->getMock()
 		);
 		$title = Title::newFromText( 'Test' );
-		$skin->expects( $this->any() )
-			->method( 'getTitle' )
-			->will( $this->returnValue( $title ) );
+		$testContext = RequestContext::getMain();
+		$testContext->setTitle( $title );
 
+		$skin->setContext ( $testContext );
 		$skin->setSkinOptions( [
 			'fontChanger' => $fontchangerValue,
 			'backToTop' => $backToTopValue,