Remove scrollX/Y setting from tests

lib/jsdom/living/events/MouseEvent-impl.js

@@ -41,17 +41,13 @@ class MouseEventImpl extends UIEventImpl {
     return this.pageY;
   }
 
-  /** @override */
   get target() {
     return super.target;
   }
 
-  /**
-   * @override
-   * calculate the event position when the target is set so that it's stable during dispatch
-   */
   set target(target) {
     super.target = target;
+    // calculate the event position when the target is set so that it's stable during dispatch
     if (target) {
       const { scrollX = 0, scrollY = 0 } = wrapperForImpl(this.view) ?? {};
       this._pageX = this.clientX + scrollX;

test/web-platform-tests/to-upstream/html/editing/activation/click-event-properties.html

@@ -90,6 +90,31 @@
 
 }, "clicking using click() should produce an event object with the correct MouseEventInit values");
 
+test(() => {
+  const e = new MouseEvent("click", {
+    clientX: 1, clientY: 2, view: window
+  });
+  assert_equals(e.x, 1);
+  assert_equals(e.y, 2);
+  assert_equals(e.pageX, 1);
+  assert_equals(e.pageY, 2);
+  assert_equals(e.offsetX, 1);
+  assert_equals(e.offsetY, 2);
+}, "MouseEvent should provide the correct computed values when the dispatch flag is not set");
+
+async_test(t => {
+  const element = document.querySelector("button");
+  element.addEventListener("click", t.step_func_done(e => {
+    assert_equals(e.pageX, 1);
+    assert_equals(e.pageY, 2);
+    assert_equals(e.offsetX, 1);
+    assert_equals(e.offsetY, 2);
+  }));
+  element.dispatchEvent(new MouseEvent("click", {
+    clientX: 1, clientY: 2, view: window
+  }));
+}, "MouseEvent should provide the correct computed values when the dispatch flag is set");
+
 test(() => {
   const e = new MouseEvent("click", {
     screenX: 1.5, screenY: 2.5, clientX: 3.5, clientY: 4.5