Auto merge of #14630 - bd339:iss14064, r=KiChjang

Use MediaQueryListEvent for media query list change events

<!-- Please describe your changes on the following line: -->

- Implements MediaQueryListEvent interface
- Makes MediaQueryList change events conform to the [spec](https://drafts.csswg.org/cssom-view/#evaluate-media-queries-and-report-changes)
- Updates matchMedia.html test to verify that the new event type is used

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #14064

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- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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tests/wpt/mozilla/tests/css/matchMedia.html

@@ -126,12 +126,16 @@
             window.onload = function(){
 
                 var rmListener = function(x){
+                    assert_true(x instanceof MediaQueryListEvent, "Check that event is instance of MediaQueryListEvent.");
+
                     resizeTest.step(function(){
                         assert_unreached("removeListener was not successful.");
                     });
                 };
 
                 var dupListener = function(x){
+                    assert_true(x instanceof MediaQueryListEvent, "Check that event is instance of MediaQueryListEvent.");
+
                     duplicateListenerTest.step(function(){
                         assert_false(mql1.dupListenerCalled, "Check that this listener has not been called before.");
                         mql1.dupListenerCalled = true;
@@ -148,6 +152,8 @@
                 mql1.addListener(dupListener);
 
                 mql1.addListener(function(x){
+                    assert_true(x instanceof MediaQueryListEvent, "Check that event is instance of MediaQueryListEvent.");
+
                     resizeTest.step(function(){
                         assert_equals(x, mql1, "Check that the MediaQueryList passed to the handler is the same that addListener was invoked on.");
                         assert_true(x.matches, "(max-height: 50px) should now pass.");
@@ -162,6 +168,8 @@
                 });
 
                 mql1.addListener(function(x){
+                    assert_true(x instanceof MediaQueryListEvent, "Check that event is instance of MediaQueryListEvent.");
+
                     listenerOrderTest.step(function(){
                         assert_true(mql1.firstListenerCalled, "Check that the listener added last is called last.");
                     });
@@ -171,6 +179,8 @@
                 mql1.removeListener(rmListener);
 
                 mql2.addListener(function(x){
+                    assert_true(x instanceof MediaQueryListEvent, "Check that event is instance of MediaQueryListEvent.");
+
                     duplicateListenerTest.done();
                     resizeTest.step(function(){
                         assert_equals(x, mql2, "Check that the MediaQueryList passed to the handler is the same that addListener was invoked on.");

tests/wpt/mozilla/tests/mozilla/interfaces.html

@@ -143,6 +143,7 @@ test_interfaces([
   "MediaError",
   "MediaList",
   "MediaQueryList",
+  "MediaQueryListEvent",
   "MessageEvent",
   "MimeType",
   "MimeTypeArray",