message: fix bug with MASKED blending mode introduced in previous PR
diff: @@ -191,8 +191,12 @@ std::string ShaderGenerator::createVertexProgram(filament::backend::ShaderModel
  const bool litVariants = lit || material.hasShadowMultiplier;
  + // note: even if the user vertex shader is empty, we can't use the "optimized" version if
  + // we're in masked mode because fragment shader needs the color varyings
  const bool useOptimizedDepthVertexShader =
  - filament::Variant::isValidDepthVariant(variantKey) && mIsMaterialVertexShaderEmpty;
  + filament::Variant::isValidDepthVariant(variantKey) &&
  + mIsMaterialVertexShaderEmpty &&
  + material.blendingMode != BlendingMode::MASKED;
  cg.generateDefine(vs, "USE_OPTIMIZED_DEPTH_VERTEX_SHADER", useOptimizedDepthVertexShader);
  cg.generateDefine(vs, "HAS_DIRECTIONAL_LIGHTING", litVariants && variant.hasDirectionalLighting());
  