Bind DirectionalLight buffer to uniform slot even when not used

This avoids a WEBGL error causes PanoramaSkys to fail to render

drivers/gles3/rasterizer_scene_gles3.cpp

@@ -595,6 +595,7 @@ void RasterizerSceneGLES3::_setup_sky(const RenderDataGLES3 *p_render_data, cons
 			sky->reflection_dirty = true;
 		}
 
+		glBindBufferBase(GL_UNIFORM_BUFFER, SKY_DIRECTIONAL_LIGHT_UNIFORM_LOCATION, sky_globals.directional_light_buffer);
 		if (shader_data->uses_light) {
 			sky_globals.directional_light_count = 0;
 			for (int i = 0; i < (int)p_lights.size(); i++) {
@@ -678,7 +679,6 @@ void RasterizerSceneGLES3::_setup_sky(const RenderDataGLES3 *p_render_data, cons
 			}
 
 			if (light_data_dirty) {
-				glBindBufferBase(GL_UNIFORM_BUFFER, SKY_DIRECTIONAL_LIGHT_UNIFORM_LOCATION, sky_globals.directional_light_buffer);
 				glBufferData(GL_UNIFORM_BUFFER, sizeof(DirectionalLightData) * sky_globals.max_directional_lights, sky_globals.directional_lights, GL_STREAM_DRAW);
 				glBindBuffer(GL_UNIFORM_BUFFER, 0);