ShaderChunk: Moved iblIrradiance definition.

src/renderers/shaders/ShaderChunk/lights_fragment_begin.glsl.js

@@ -107,6 +107,8 @@ IncidentLight directLight;
 
 #if defined( RE_IndirectDiffuse )
 
+	vec3 iblIrradiance = vec3( 0.0 );
+
 	vec3 irradiance = getAmbientLightIrradiance( ambientLightColor );
 
 	irradiance += getLightProbeIrradiance( lightProbe, geometry );

src/renderers/shaders/ShaderChunk/lights_fragment_maps.glsl.js

@@ -15,8 +15,6 @@ export default /* glsl */`
 
 	#endif
 
-	vec3 iblIrradiance = vec3( 0.0 );
-
 	#if defined( USE_ENVMAP ) && defined( STANDARD ) && defined( ENVMAP_TYPE_CUBE_UV )
 
 		iblIrradiance += getLightProbeIndirectIrradiance( /*lightProbe,*/ geometry, maxMipLevel );