1. DomName('WebGLRenderingContext.stencilMaskSeparate')
  2. DocsEditable()
void stencilMaskSeparate(int face, int mask)

Source 

@DomName('WebGLRenderingContext.stencilMaskSeparate')
@DocsEditable()
void stencilMaskSeparate(int face, int mask) => _blink.BlinkWebGLRenderingContext.instance.stencilMaskSeparate_Callback_2_(unwrap_jso(this), face, mask);