MDL-67623 block overview: fix pagination regression

Fixed a regression caused by MDL-64194 resulting in Dashboard - Course
overview pagination not working from second page of courses onwards.

Course overview block should now do the following:
- Display no pagination controls when user has no courses
- Display no pagination controls when less than 12 courses to display
- Only display pagination controls up to the number of courses user is
enrolled in
- Work correctly when on a page greater than the second page.

blocks/myoverview/amd/src/view.js

@@ -543,11 +543,9 @@ function(
 
         // Filter out all pagination options which are too large for the amount of courses user is enrolled in.
         var totalCourseCount = parseInt(root.find(Selectors.courseView.region).attr('data-totalcoursecount'), 10);
-        if (totalCourseCount) {
-            itemsPerPage = itemsPerPage.filter(function(pagingOption) {
-                return pagingOption.value < totalCourseCount;
-            });
-        }
+        itemsPerPage = itemsPerPage.filter(function(pagingOption) {
+            return pagingOption.value < totalCourseCount || pagingOption.value === 0;
+        });
 
         var filters = getFilterValues(root);
         var config = $.extend({}, DEFAULT_PAGED_CONTENT_CONFIG);
@@ -602,7 +600,8 @@ function(
                                 pageCourses = $.merge(loadedPages[currentPage].courses, courses.slice(0, nextPageStart));
                             }
                         } else {
-                            nextPageStart = pageData.limit;
+                            // When the page limit is zero, there is only one page of courses, no start for next page.
+                            nextPageStart = pageData.limit || false;
                             pageCourses = (pageData.limit > 0) ? courses.slice(0, pageData.limit) : courses;
                         }
 
@@ -611,8 +610,8 @@ function(
                             courses: pageCourses
                         };
 
-                        // Set up the next page
-                        var remainingCourses = nextPageStart ? courses.slice(nextPageStart, courses.length) : [];
+                        // Set up the next page (if there is more than one page).
+                        var remainingCourses = nextPageStart !== false ? courses.slice(nextPageStart, courses.length) : [];
                         if (remainingCourses.length) {
                             loadedPages[currentPage + 1] = {
                                 courses: remainingCourses

blocks/myoverview/classes/output/main.php

@@ -202,8 +202,9 @@ public function __construct($grouping, $sort, $view, $paging, $customfieldvalue
         // Check and remember the given view.
         $this->view = $view ? $view : BLOCK_MYOVERVIEW_VIEW_CARD;
 
-        // Check and remember the given page size.
-        if ($paging == BLOCK_MYOVERVIEW_PAGING_ALL) {
+        // Check and remember the given page size, `null` indicates no page size set
+        // while a `0` indicates a paging size of `All`.
+        if (!is_null($paging) && $paging == BLOCK_MYOVERVIEW_PAGING_ALL) {
             $this->paging = BLOCK_MYOVERVIEW_PAGING_ALL;
         } else {
             $this->paging = $paging ? $paging : BLOCK_MYOVERVIEW_PAGING_12;