WebGL 2: add read/write framebuffer binding points to related APIs

Source/core/html/canvas/WebGL2RenderingContextBase.h

Index: Source/core/html/canvas/WebGL2RenderingContextBase.h
diff --git a/Source/core/html/canvas/WebGL2RenderingContextBase.h b/Source/core/html/canvas/WebGL2RenderingContextBase.h
index 9137ffe8a87807ed2b7e23f2dde2413bb2b42564..33041db69b8c2e04d9bf759a575be904f8f7501b 100644
--- a/Source/core/html/canvas/WebGL2RenderingContextBase.h
+++ b/Source/core/html/canvas/WebGL2RenderingContextBase.h
@@ -162,9 +162,11 @@ public:
     /* WebGLRenderingContextBase overrides */
     void initializeNewContext() override;
     void bindFramebuffer(GLenum target, WebGLFramebuffer*) override;
+    void deleteFramebuffer(WebGLFramebuffer*) override;
     ScriptValue getParameter(ScriptState*, GLenum pname) override;
     ScriptValue getTexParameter(ScriptState*, GLenum target, GLenum pname) override;
     ScriptValue getFramebufferAttachmentParameter(ScriptState*, GLenum target, GLenum attachment, GLenum pname) override;
+    void restoreCurrentFramebuffer() override;
 
     DECLARE_VIRTUAL_TRACE();
 
@@ -188,6 +190,7 @@ protected:
     WebGLTexture* validateTextureBinding(const char* functionName, GLenum target, bool useSixEnumsForCubeMap) override;
     bool validateFramebufferTarget(GLenum target) override;
     WebGLFramebuffer* getFramebufferBinding(GLenum target) override;
+    GLenum boundFramebufferColorFormat() override;
 
     RefPtrWillBeMember<WebGLFramebuffer> m_readFramebufferBinding;
 };