MDL-39964 deprecate can_use_rotated_text()

This probably should never have landed in moodlelib anyway, as it was
only used in the completion report

lib/deprecatedlib.php

@@ -4676,3 +4676,14 @@ function convert_tabrows_to_tree($tabrows, $selected, $inactive, $activated) {
 
     return $subtree;
 }
+
+/**
+ * Can handle rotated text. Whether it is safe to use the trickery in textrotate.js.
+ *
+ * @deprecated since 2.5 - do not use, the textrotate.js will work it out automatically
+ * @return bool True for yes, false for no
+ */
+function can_use_rotated_text() {
+    debugging('can_use_rotated_text() is deprecated since Moodle 2.5. JS feature detection is used automatically.', DEBUG_DEVELOPER);
+    return true;
+}

lib/moodlelib.php

@@ -9111,17 +9111,6 @@ function get_browser_version_classes() {
     return $classes;
 }
 
-/**
- * Can handle rotated text. Whether it is safe to use the trickery in textrotate.js.
- *
- * @return bool True for yes, false for no
- */
-function can_use_rotated_text() {
-    return check_browser_version('MSIE', 9) || check_browser_version('Firefox', 2) ||
-            check_browser_version('Chrome', 21) || check_browser_version('Safari', 536.25) ||
-            check_browser_version('Opera', 12) || check_browser_version('Safari iOS', 533);
-}
-
 /**
  * Determine if moodle installation requires update
  *