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_(this, face, mask);