MDL-27857 Assignment does not use form tag to render portfolio export…

… control widget

When this code was used as a part of the grading screen, the default
PORTFOLIO_ADD_FULL_FORM widget led to nested form elements. This patch replaces
the form widget with a plain text link that can be embedded safely.

mod/assignment/lib.php

@@ -1927,7 +1927,7 @@ function print_user_files($userid=0, $return=false) {
             }
             if ($CFG->enableportfolios && count($files) > 1  && $this->portfolio_exportable() && has_capability('mod/assignment:exportownsubmission', $this->context)) {
                 $button->set_callback_options('assignment_portfolio_caller', array('id' => $this->cm->id), '/mod/assignment/locallib.php');
-                $output .= '<br />'  . $button->to_html();
+                $output .= '<br />'  . $button->to_html(PORTFOLIO_ADD_TEXT_LINK);
             }
         }
 

mod/assignment/renderer.php

@@ -98,7 +98,7 @@ public function __construct($context, $itemid, $filearea='submission') {
                 $button = new portfolio_add_button();
                 $button->set_callback_options('assignment_portfolio_caller', array('id' => $this->cm->id), '/mod/assignment/locallib.php');
                 $button->reset_formats();
-                $this->portfolioform = $button->to_html();
+                $this->portfolioform = $button->to_html(PORTFOLIO_ADD_TEXT_LINK);
             }
         }
         $this->preprocess($this->dir, $filearea);