Revert "Outputting UTF-8 charset in document header irrespective of mimetype."

This reverts commit 353f58c231.

Even though outputting UTF-8 by default at all times is a good thing,
it shouldn't be forced in startHTML().

lib/htmloutputter.php

@@ -106,7 +106,7 @@ class HTMLOutputter extends XMLOutputter
             }
         }
 
-        header('Content-Type: '.$type.'; charset=UTF-8');
+        header('Content-Type: '.$type);
 
         $this->extraHeaders();
         if (preg_match("/.*\/.*xml/", $type)) {

lib/util.php

@@ -1165,7 +1165,7 @@ function common_negotiate_type($cprefs, $sprefs)
     }
 
     if ('text/html' === $besttype) {
-        return "text/html";
+        return "text/html; charset=utf-8";
     }
     return $besttype;
 }