--- a/dom/html/HTMLSourceElement.cpp
+++ b/dom/html/HTMLSourceElement.cpp
@@ -9,17 +9,16 @@
 
 #include "mozilla/dom/HTMLImageElement.h"
 #include "mozilla/dom/ResponsiveImageSelector.h"
 #include "mozilla/dom/MediaList.h"
 #include "mozilla/dom/MediaSource.h"
 
 #include "nsGkAtoms.h"
 
-#include "nsCSSParser.h"
 #include "nsHostObjectProtocolHandler.h"
 
 #include "mozilla/Preferences.h"
 
 NS_IMPL_NS_NEW_HTML_ELEMENT(Source)
 
 namespace mozilla {
 namespace dom {
@@ -84,17 +83,16 @@ void
 HTMLSourceElement::UpdateMediaList(const nsAttrValue* aValue)
 {
   mMediaList = nullptr;
   nsString mediaStr;
   if (!aValue || (mediaStr = aValue->GetStringValue()).IsEmpty()) {
     return;
   }
 
-  nsCSSParser cssParser;
   mMediaList = MediaList::Create(OwnerDoc()->GetStyleBackendType(), mediaStr);
 }
 
 nsresult
 HTMLSourceElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
                                 const nsAttrValue* aValue,
                                 const nsAttrValue* aOldValue,
                                 nsIPrincipal* aMaybeScriptedPrincipal,