LibWeb/WebGL: Forward the render context ref count to HTMLCanvasElement

This allows HTMLCanvasElement and WebGL rendering contexts to share
their lifetime, as JS allows them to arbitrarily access them at any
time and WebGLRCB.canvas expects a non-null return value.

Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.cpp

@@ -12,7 +12,7 @@
 namespace Web::WebGL {
 
 WebGLRenderingContextBase::WebGLRenderingContextBase(HTML::HTMLCanvasElement& canvas_element, NonnullOwnPtr<GL::GLContext> context, WebGLContextAttributes context_creation_parameters, WebGLContextAttributes actual_context_parameters)
-    : m_canvas_element(canvas_element)
+    : RefCountForwarder(canvas_element)
     , m_context(move(context))
     , m_context_creation_parameters(move(context_creation_parameters))
     , m_actual_context_parameters(move(actual_context_parameters))
@@ -67,15 +67,23 @@ void WebGLRenderingContextBase::present()
     }
 }
 
+HTML::HTMLCanvasElement& WebGLRenderingContextBase::canvas_element()
+{
+    return ref_count_target();
+}
+
+HTML::HTMLCanvasElement const& WebGLRenderingContextBase::canvas_element() const
+{
+    return ref_count_target();
+}
+
 void WebGLRenderingContextBase::needs_to_present()
 {
     m_should_present = true;
 
-    if (!m_canvas_element)
-        return;
-    if (!m_canvas_element->layout_node())
+    if (!canvas_element().layout_node())
         return;
-    m_canvas_element->layout_node()->set_needs_display();
+    canvas_element().layout_node()->set_needs_display();
 }
 
 void WebGLRenderingContextBase::set_error(GLenum error)

Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.h

@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/RefCounted.h>
+#include <AK/RefCountForwarder.h>
 #include <AK/WeakPtr.h>
 #include <AK/Weakable.h>
 #include <LibGL/GLContext.h>
@@ -16,7 +16,7 @@
 namespace Web::WebGL {
 
 class WebGLRenderingContextBase
-    : public RefCounted<WebGLRenderingContextBase>
+    : public RefCountForwarder<HTML::HTMLCanvasElement>
     , public Weakable<WebGLRenderingContextBase> {
 public:
     virtual ~WebGLRenderingContextBase();
@@ -63,8 +63,6 @@ protected:
     WebGLRenderingContextBase(HTML::HTMLCanvasElement& canvas_element, NonnullOwnPtr<GL::GLContext> context, WebGLContextAttributes context_creation_parameters, WebGLContextAttributes actual_context_parameters);
 
 private:
-    WeakPtr<HTML::HTMLCanvasElement> m_canvas_element;
-
     NonnullOwnPtr<GL::GLContext> m_context;
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#context-creation-parameters
@@ -87,6 +85,9 @@ private:
 
     GLenum m_error { GL_NO_ERROR };
 
+    HTML::HTMLCanvasElement& canvas_element();
+    HTML::HTMLCanvasElement const& canvas_element() const;
+
     void needs_to_present();
     void set_error(GLenum error);
 };