MDL-75108 block_html: Search tries to index directory entries

Search attach_files function should only attach indexable files,
not directory entries which are 0 bytes and cannot be indexed.

blocks/html/classes/search/content.php

@@ -83,7 +83,8 @@ public function attach_files($document) {
 
         $context = \context::instance_by_id($document->get('contextid'));
 
-        $files = $fs->get_area_files($context->id, 'block_html', 'content');
+        $files = $fs->get_area_files($context->id, 'block_html', 'content',
+                false, 'itemid, filepath, filename', false);
         foreach ($files as $file) {
             $document->add_stored_file($file);
         }

blocks/html/tests/search_content_test.php

@@ -137,11 +137,9 @@ public function test_search_area() {
             $this->assertCount(0, $doc->get_files());
             $area->attach_files($doc);
             $files = $doc->get_files();
-            $this->assertCount(2, $files);
+            // The directory entry should NOT be provided for indexing.
+            $this->assertCount(1, $files);
             foreach ($files as $file) {
-                if ($file->is_directory()) {
-                    continue;
-                }
                 $this->assertEquals('file.txt', $file->get_filename());
                 $this->assertEquals('File content', $file->get_content());
             }