LightingSimpleSpecular_DirLightmap method is not getting called when using General GI->Directional mode->directional/directional Specular settings for baking lights.

Steps to reproduce:
1.Open attached project "TestingLight".
2.Open "main" scene.
3.Open Lighting tab.
4.Set "Directional mode" to "non-directional"
5.Build lighting
- cube colour changes to red(this is expected)
6.Set "Directional mode" to "directional"
- cube colour does not change to red because LightingSimpleSpecular_DirLightmap is not getting called.

Current result: LightingSimpleSpecular_DirLightmap method is not getting called when Directional mode is set to "directional".

Reproduced on: 5.5.0b1, 5.4.0p2, 5.4.0f3, 5.3.6f1, 5.3.5f1, 5.2.3p3.