Unused struct definition is not dropped

[LJ1102]

When I optimized my shader I eventually optimized out the usage of a struct but forgot about the definition, later I found out that the definition remained in the minified shader source, despite not being used anywhere.

Reproducible test case (in web version).

struct Test { float A, B; } T;
void main(){
    gl_FragColor=vec4(1,0,0,1);
}