Bug 1642895 - Remove unused nsFontFaceLoader::Init declaration. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D77997

layout/style/nsFontFaceLoader.h

@@ -35,8 +35,6 @@ class nsFontFaceLoader final : public nsIStreamLoaderObserver,
   NS_DECL_NSISTREAMLOADEROBSERVER
   NS_DECL_NSIREQUESTOBSERVER
 
-  // initiate the load
-  nsresult Init();
   // cancel the load and remove its reference to mFontFaceSet
   void Cancel();