Issue #2056837 by longwave: Fixed Modules can no longer alter page_bottom().

core/includes/theme.inc

@@ -2610,7 +2610,7 @@ function template_preprocess_html(&$variables) {
   }
   $variables['page_bottom'] = array();
   if (isset($variables['page']['page_bottom'])) {
-    $variables['page_bottom'] = drupal_render($variables['page']['page_bottom']);
+    $variables['page_bottom'][]['#markup'] = drupal_render($variables['page']['page_bottom']);
   }
 
   // Add footer scripts as '#markup' so they can be rendered with other

core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php

@@ -276,6 +276,7 @@ function testPreprocessHtml() {
     $this->drupalGet('');
     $attributes = $this->xpath('/html/body[@theme_test_page_variable="Page variable is an array."]');
     $this->assertTrue(count($attributes) == 1, 'In template_preprocess_html(), the page variable is still an array (not rendered yet).');
+    $this->assertText('theme test page bottom markup', 'Modules are able to set the page bottom region.');
   }
 
 

core/modules/system/tests/modules/theme_test/theme_test.module

@@ -162,6 +162,13 @@ function theme_test_preprocess_html(&$variables) {
   }
 }
 
+/**
+ * Implements hook_page_alter().
+ */
+function theme_test_page_alter(&$page) {
+  $page['page_bottom']['theme_test_page_bottom'] = array('#markup' => 'theme test page bottom markup');
+}
+
 /**
  * Theme function for testing theme('theme_test_foo').
  */