message: Remove usage of the invariant keyword.
diff: @@ -79,13 +79,6 @@ io::sstream& CodeGenerator::generateProlog(io::sstream& out, ShaderType type,
  out << "precision " << precision << " float;\n";
  out << "precision " << precision << " int;\n";
  - // The version of the Metal Shading Language (MSL) we use does not have the invariant qualifier.
  - // New versions of MSL (> 2.1) have it, but we want to support older devices.
  - if (type == ShaderType::VERTEX && mTargetApi != TargetApi::METAL) {
  - out << "\n";
  - out << "invariant gl_Position;\n";
  - }
  -
  out << SHADERS_COMMON_TYPES_FS_DATA;
  out << "\n";
  