Bug 1965183 - Consider to set microtask level to 0 when dispatching events, r=masayuki,webdriver-reviewers,whimboo

Differential Revision: https://phabricator.services.mozilla.com/D248391

remote/marionette/actors/MarionetteCommandsChild.sys.mjs

@@ -71,6 +71,13 @@ export class MarionetteCommandsChild extends JSWindowActorChild {
     const { eventName, details } = options;
     const win = this.contentWindow;
 
+    const windowUtils = win.windowUtils;
+    const microTaskLevel = windowUtils.microTaskLevel;
+    // Since we're being called as a webidl callback,
+    // CallbackObjectBase::CallSetup::CallSetup has increased the microtask
+    // level. Undo that temporarily so that microtask handling works closer
+    // the way it would work when dispatching events natively.
+    windowUtils.microTaskLevel = 0;
     try {
       switch (eventName) {
         case "synthesizeKeyDown":
@@ -114,6 +121,8 @@ export class MarionetteCommandsChild extends JSWindowActorChild {
       }
 
       throw e;
+    } finally {
+      windowUtils.microTaskLevel = microTaskLevel;
     }
   }
 

remote/webdriver-bidi/modules/windowglobal/input.sys.mjs

@@ -52,6 +52,14 @@ class InputModule extends WindowGlobalBiDiModule {
   async _dispatchEvent(options) {
     const { eventName, details } = options;
 
+    const windowUtils = this.messageHandler.window.windowUtils;
+    const microTaskLevel = windowUtils.microTaskLevel;
+    // Since we're being called as a webidl callback,
+    // CallbackObjectBase::CallSetup::CallSetup has increased the microtask
+    // level. Undo that temporarily so that microtask handling works closer
+    // the way it would work when dispatching events natively.
+    windowUtils.microTaskLevel = 0;
+
     try {
       switch (eventName) {
         case "synthesizeKeyDown":
@@ -98,6 +106,8 @@ class InputModule extends WindowGlobalBiDiModule {
       }
 
       throw e;
+    } finally {
+      windowUtils.microTaskLevel = microTaskLevel;
     }
   }