Fix crash when event.currentTarget is used with EventTargetTBase

src/browser/html/window.zig

@@ -387,4 +387,19 @@ test "Browser.HTML.Window" {
         .{ "window.setTimeout(() => {longCall = true}, 5001);", null },
         .{ "longCall;", "false" },
     }, .{});
+
+    // window event target
+    try runner.testCases(&.{
+        .{
+            \\ let called = false;
+            \\ window.addEventListener("ready", (e) => {
+            \\   called = (e.currentTarget == window);
+            \\ }, {capture: false, once: false});
+            \\ const evt = new Event("ready", { bubbles: true, cancelable: false });
+            \\ window.dispatchEvent(evt);
+            \\ called;
+            ,
+            "true",
+        },
+    }, .{});
 }

src/browser/netsurf.zig

@@ -775,6 +775,17 @@ pub const EventTargetTBase = extern struct {
         .add_event_listener = add_event_listener,
         .iter_event_listener = iter_event_listener,
     },
+
+    // When we dispatch the event, we need to provide a target. In reality, the
+    // target is the container of this EventTargetTBase. But we can't pass that
+    // to _dom_event_target_dispatch, because it expects a dom_event_target.
+    // If you try to pass an non-event_target, you'll get weird behavior. For
+    // example, libdom might dom_node_ref that memory. Say we passed a *Window
+    // as the target, what happens if libdom calls dom_node_ref(window)? If
+    // you're lucky, you'll crash. If you're unlucky, you'll increment a random
+    // part of the window structure.
+    refcnt: u32 = 0,
+
     eti: c.dom_event_target_internal = c.dom_event_target_internal{ .listeners = null },
 
     pub fn add_event_listener(et: [*c]c.dom_event_target, t: [*c]c.dom_string, l: ?*c.struct_dom_event_listener, capture: bool) callconv(.C) c.dom_exception {