make getComptedStyle return an empty CSSStyleDeclaration

src/browser/cssom/css_style_declaration.zig

@@ -33,6 +33,11 @@ pub const CSSStyleDeclaration = struct {
     store: std.StringHashMapUnmanaged(Property),
     order: std.ArrayListUnmanaged([]const u8),
 
+    pub const empty: CSSStyleDeclaration = .{
+        .store = .empty,
+        .order = .empty,
+    };
+
     const Property = struct {
         value: []const u8,
         priority: bool,

src/browser/html/elements.zig

@@ -109,10 +109,7 @@ pub const HTMLElement = struct {
     pub const prototype = *Element;
     pub const subtype = .node;
 
-    style: CSSStyleDeclaration = .{
-        .store = .{},
-        .order = .{},
-    },
+    style: CSSStyleDeclaration = .empty,
 
     pub fn get_style(e: *parser.ElementHTML, state: *SessionState) !*CSSStyleDeclaration {
         const self = try state.getOrCreateNodeWrapper(HTMLElement, @ptrCast(e));

src/browser/html/window.zig

@@ -31,6 +31,7 @@ const Console = @import("../console/console.zig").Console;
 const EventTarget = @import("../dom/event_target.zig").EventTarget;
 const MediaQueryList = @import("media_query_list.zig").MediaQueryList;
 const Performance = @import("performance.zig").Performance;
+const CSSStyleDeclaration = @import("../cssom/css_style_declaration.zig").CSSStyleDeclaration;
 
 const storage = @import("../storage/storage.zig");
 
@@ -237,13 +238,13 @@ pub const Window = struct {
         return timer_id;
     }
 
-    // NOT IMPLEMENTED - This is a dummy implementation that always returns null to deter PlayWright from using this path to solve click.js.
-    // returns an object containing the values of all CSS properties of an element, after applying active stylesheets and resolving any basic computation those values may contain.
-    pub fn _getComputedStyle(_: *Window, element: *parser.Element, pseudo_element: ?[]const u8) !?void {
+    // TODO: getComputedStyle should return a read-only CSSStyleDeclaration.
+    // We currently don't have a read-only one, so we return a new instance on
+    // each call.
+    pub fn _getComputedStyle(_: *Window, element: *parser.Element, pseudo_element: ?[]const u8) !CSSStyleDeclaration {
         _ = element;
         _ = pseudo_element;
-        log.warn("Not implemented function getComputedStyle called, null returned", .{});
-        return null;
+        return .empty;
     }
 };