LibWeb: Add WebSocket bindings

The WebSocket bindings match the original specification from the
WHATWG living standard, but do not match the later update of the
standard that involves FETCH. The FETCH update will be handled later
since the changes would also affect XMLHttpRequest.

Userland/Libraries/LibWeb/Forward.h

@@ -58,6 +58,7 @@ enum class QuirksMode;
 
 namespace Web::HTML {
 class CanvasRenderingContext2D;
+class CloseEvent;
 class EventHandler;
 class HTMLAnchorElement;
 class HTMLAreaElement;
@@ -133,6 +134,8 @@ class HTMLUListElement;
 class HTMLUnknownElement;
 class HTMLVideoElement;
 class ImageData;
+class MessageEvent;
+class WebSocket;
 }
 
 namespace Web::HighResolutionTime {
@@ -201,6 +204,7 @@ class CSSStyleDeclarationWrapper;
 class CSSStyleSheetWrapper;
 class CanvasRenderingContext2DWrapper;
 class CharacterDataWrapper;
+class CloseEventWrapper;
 class CommentWrapper;
 class DocumentFragmentWrapper;
 class DocumentTypeWrapper;
@@ -285,6 +289,7 @@ class HTMLUnknownElementWrapper;
 class HTMLVideoElementWrapper;
 class ImageDataWrapper;
 class LocationObject;
+class MessageEventWrapper;
 class MouseEventWrapper;
 class NodeWrapper;
 class PerformanceTimingWrapper;
@@ -303,6 +308,7 @@ class StyleSheetWrapper;
 class StyleSheetListWrapper;
 class TextWrapper;
 class UIEventWrapper;
+class WebSocketWrapper;
 class WindowObject;
 class Wrappable;
 class Wrapper;