simplified some code

src/Shaders/ShadersInclude/hdrFilteringFunctions.fx

@@ -1,10 +1,5 @@
 #ifdef NUM_SAMPLES
-	#ifdef WEBGL2
-		#define ZERO 0u
-	#else
-		#define ZERO 0
-	#endif
-	#if NUM_SAMPLES > ZERO
+	#if NUM_SAMPLES > 0
 		const float NUM_SAMPLES_FLOAT = float(NUM_SAMPLES);
 		const float NUM_SAMPLES_FLOAT_INVERSED = 1. / NUM_SAMPLES_FLOAT;
 

src/Shaders/ShadersInclude/pbrBlockReflection.fx

@@ -267,7 +267,7 @@
                     irradianceVector.y *= -1.0;
                 #endif
 
-                #if defined(WEBGL2) && defined(REALTIME_FILTERING)
+                #if defined(REALTIME_FILTERING)
                     environmentIrradiance = irradiance(reflectionSampler, irradianceVector, vReflectionFilteringInfo);
                 #else
                     environmentIrradiance = computeEnvironmentIrradiance(irradianceVector);

src/Shaders/ShadersInclude/pbrBlockSubSurface.fx

@@ -317,7 +317,7 @@ struct subSurfaceOutParams
         #endif
 
         #if defined(USESPHERICALFROMREFLECTIONMAP)
-            #if defined(WEBGL2) && defined(REALTIME_FILTERING)
+            #if defined(REALTIME_FILTERING)
                 vec3 refractionIrradiance = irradiance(reflectionSampler, -irradianceVector, vReflectionFilteringInfo);
             #else
                 vec3 refractionIrradiance = computeEnvironmentIrradiance(-irradianceVector);