MAGETWO-44713: Flashing error while Web Installation

- Updates to accommodate code review comment

Author: Ankur Kaneria

setup/src/Magento/Setup/Controller/Install.php

@@ -128,7 +128,7 @@ public function progressAction()
         // "install.log" file may not be created yet. Check the "install.log" is created before
         // trying to read from it.
         if (!$this->log->logfileExists()) {
-            return $json->setVariables(['progress' => $percent, 'success' => $success, 'console' => $contents]);
+            return $json->setVariables(['progress' => $percent, 'success' => true, 'console' => $contents]);
         }
 
         try {

setup/src/Magento/Setup/Test/Unit/Controller/InstallTest.php

@@ -161,7 +161,7 @@ public function testProgressActionNoInstallLogFile()
         $variables = $jsonModel->getVariables();
         $this->assertArrayHasKey('success', $variables);
         $this->assertArrayHasKey('console', $variables);
-        $this->assertFalse($variables['success']);
+        $this->assertTrue($variables['success']);
         $this->assertEmpty($variables['console']);
         $this->assertSame(0, $variables['progress']);
     }