refactored Pjax. Added title change support. [skip ci]

framework/widgets/Pjax.php

@@ -89,15 +89,17 @@ class Pjax extends Widget
 			$this->options['id'] = $this->getId();
 		}
 
+		if ($this->requiresPjax()) {
 			ob_start();
 			ob_implicit_flush(false);
-
-		if ($this->requiresPjax()) {
 			$view = $this->getView();
 			$view->clear();
 			$view->beginPage();
 			$view->head();
 			$view->beginBody();
+			if ($view->title !== null) {
+				echo Html::tag('title', Html::encode($view->title));
+			}
 		}
 		echo Html::beginTag('div', $this->options);
 	}
@@ -108,15 +110,18 @@ class Pjax extends Widget
 	public function run()
 	{
 		echo Html::endTag('div');
-		if ($requiresPjax = $this->requiresPjax()) {
+
+		if (!$this->requiresPjax()) {
+			$this->registerClientScript();
+			return;
+		}
+
 		$view = $this->getView();
 		$view->endBody();
 		$view->endPage(true);
-		}
 
 		$content = ob_get_clean();
 
-		if ($requiresPjax) {
 		// only need the content enclosed within this widget
 		$response = Yii::$app->getResponse();
 		$level = ob_get_level();
@@ -131,10 +136,6 @@ class Pjax extends Widget
 			ob_start();
 			ob_implicit_flush(false);
 		}
-		} else {
-			$this->registerClientScript();
-			echo $content;
-		}
 	}
 
 	/**