Bug 1603690 - Remove a redundant return statement and removed empty lines. r=Ehsan

Differential Revision: https://phabricator.services.mozilla.com/D57086

--HG--
extra : moz-landing-system : lando

dom/script/ScriptLoader.cpp

@@ -2373,8 +2373,6 @@ void ScriptLoader::ProcessDynamicImport(ModuleLoadRequest* aRequest) {
   if (NS_FAILED(rv)) {
     FinishDynamicImport(aRequest, rv);
   }
-
-  return;
 }
 
 void ScriptLoader::FireScriptAvailable(nsresult aResult,