[FIX] web: allow to unregister multiple listener from the same target

Steps to reproduce
==================

- Register two events listener on the same target
- Unregister them

Only the first one is unregistered

Cause of the issue
==================

`cbs` is used instead of `listeners`. This means that after any `.off`
call, the target is removed from the Map and it is not possible anymore
to unregister any events for it

closes odoo/odoo#118739

X-original-commit: 345dd30fdc627ada212a8eaa6f9817bbdaf5d3a3
Signed-off-by: Samuel Degueldre <sad@odoo.com>
Signed-off-by: Hubert Van De Walle <huvw@odoo.com>

addons/web/static/src/owl2_compatibility/event_target.js

@@ -33,8 +33,8 @@
             for (const callback of cbs) {
                 this.removeEventListener(type, callback);
             }
-            delete cbs[type];
-            if (Object.keys(cbs).length === 0) {
+            delete listeners[type];
+            if (Object.keys(listeners).length === 0) {
                 this.targetsCallbacks.delete(target);
             }
         }

addons/web/static/tests/legacy/owl_compatibility_tests.js

@@ -21,6 +21,7 @@
 
     const {
         Component,
+        EventBus,
         onError,
         onMounted,
         onWillDestroy,
@@ -1677,4 +1678,30 @@
 
             await mount(MyComponent, getFixture(), { env: legacyEnv });
         });
+
+        QUnit.module("EventBus");
+
+        QUnit.test("unregister multiple listener from the same target", async function (assert) {
+            const target = Symbol("test");
+            const bus = new EventBus();
+            let i = 0;
+
+            bus.on("a", target, () => assert.step(`a:${i++}`));
+            bus.on("b", target, () => assert.step(`b:${i++}`));
+
+            bus.trigger("a");
+            bus.trigger("b");
+
+            bus.off("a", target);
+            bus.off("b", target);
+
+            bus.trigger("a");
+            bus.trigger("b");
+
+            assert.verifySteps([
+                "a:0",
+                "b:1",
+            ], "callback should not be called after unregistering them");
+        });
+
     });