add polyfill for tests

Author: krichprollsch

src/browser/polyfill/focusevent.js

@@ -0,0 +1,18 @@
+(function() {
+  // critically in Phantom JS it is an object so can't be used as a constructor.
+  if (typeof FocusEvent !== 'function') {
+    window.FocusEvent = function(eventType, init) {
+      init = init || {};
+      var focusEvent = document.createEvent('Event');
+      focusEvent.initUIEvent(
+        eventType,
+        false,
+        false,
+        window,
+        init.detail
+      );
+
+      return focusEvent;
+    }
+  }
+})();

src/browser/polyfill/polyfill.zig

@@ -28,6 +28,8 @@ const modules = [_]struct {
     source: []const u8,
 }{
     .{ .name = "polyfill-fetch", .source = @import("fetch.zig").source },
+    .{ .name = "polyfill-focusevent", .source = @import("shadowdom.zig").focusevent },
+    .{ .name = "polyfill-shadowdom", .source = @import("shadowdom.zig").source },
 };
 
 pub fn load(allocator: Allocator, js_context: *Env.JsContext) !void {