Bug 1241702 - Allow unsized DEPTH_STENCIL for RBs in WebGL 2. - r=kamidphish

dom/canvas/WebGLFormats.cpp

@@ -822,6 +822,9 @@ FormatUsageAuthority::CreateForWebGL2(gl::GLContext* gl)
     if (!AddUnsizedFormats(ptr, gl))
         return nullptr;
 
+    ptr->AllowRBFormat(LOCAL_GL_DEPTH_STENCIL,
+                       ptr->GetUsage(EffectiveFormat::DEPTH24_STENCIL8));
+
     if (gfxPrefs::WebGL2CompatMode()) {
         AddSimpleUnsized(ptr, LOCAL_GL_RGBA, LOCAL_GL_FLOAT, EffectiveFormat::RGBA32F);
         AddSimpleUnsized(ptr, LOCAL_GL_RGB , LOCAL_GL_FLOAT, EffectiveFormat::RGB32F );