LibWeb/WebGL: Implement drawingBufferWidth and drawingBufferHeight

Author: https://github.com/kalenikaliaksandr
Commit: c199be061a
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2878
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/gmta

Libraries/LibWeb/WebGL/WebGLRenderingContext.cpp

@@ -171,4 +171,16 @@ JS::Object* WebGLRenderingContext::get_extension(String const&)
     return nullptr;
 }
 
+WebIDL::Long WebGLRenderingContext::drawing_buffer_width() const
+{
+    auto size = canvas_for_binding()->bitmap_size_for_canvas();
+    return size.width();
+}
+
+WebIDL::Long WebGLRenderingContext::drawing_buffer_height() const
+{
+    auto size = canvas_for_binding()->bitmap_size_for_canvas();
+    return size.height();
+}
+
 }