Bug 1759881 - Part 5: Remove microtask checkpoints from the module loader in couple of places r=smaug

This removes the microtask checkpoint when instantiating modules and moves the
one when creating a module script to the the script loader.

Differential Revision: https://phabricator.services.mozilla.com/D141252

dom/script/ScriptLoader.cpp

@@ -1106,6 +1106,13 @@ bool ScriptLoader::ProcessInlineScript(nsIScriptElement* aElement,
       }
     }
 
+    {
+      // We must perform a microtask checkpoint when inserting script elements
+      // as specified by: https://html.spec.whatwg.org/#parsing-main-incdata
+      // For the non-inline module cases this happens in ProcessRequest.
+      mozilla::nsAutoMicroTask mt;
+    }
+
     nsresult rv = mModuleLoader->ProcessFetchedModuleSource(modReq);
     if (NS_FAILED(rv)) {
       ReportErrorToConsole(modReq, rv);