constructor(parser) {
    this.parser = parser;
    this.name = EXTENSIONS.KHR_MATERIALS_EMISSIVE_STRENGTH;
  }
Materials Emissive Strength Extension

Specification: https://github.com/KhronosGroup/glTF/blob/5768b3ce0ef32bc39cdf1bef10b948586635ead3/extensions/2.0/Khronos/KHR_materials_emissive_strength/README.md