minor #23216 Remove HHVM support (second edition) (Nek-)

This PR was squashed before being merged into the 4.0-dev branch (closes #23216).

Discussion
----------

Remove HHVM support (second edition)

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | not needed

This PR removes HHVM compatiblity following #22758 as some things were missing. It also removes some useless comments.

Commits
-------

471b84c Remove HHVM support (second edition)

Author: nicolas-grekas

Loader/IcuDatFileLoader.php

@@ -39,7 +39,6 @@ public function load($resource, $locale, $domain = 'messages')
         try {
             $rb = new \ResourceBundle($locale, $resource);
         } catch (\Exception $e) {
-            // HHVM compatibility: constructor throws on invalid resource
             $rb = null;
         }
 

Loader/IcuResFileLoader.php

@@ -39,7 +39,6 @@ public function load($resource, $locale, $domain = 'messages')
         try {
             $rb = new \ResourceBundle($locale, $resource);
         } catch (\Exception $e) {
-            // HHVM compatibility: constructor throws on invalid resource
             $rb = null;
         }