Fix IntegrateSpecularGGXIBLRef() for the standard GGX

ScriptableRenderPipeline/HDRenderPipeline/Material/Lit/LitReference.hlsl

 // Ref: Moving Frostbite to PBR (Appendix A)
 float3 IntegrateSpecularGGXIBLRef(LightLoopContext lightLoopContext,
                                   float3 V, PreLightData preLightData, EnvLightData lightData, BSDFData bsdfData,
-                                  uint sampleCount = 4096)
+                                  uint sampleCount = 2048)
-    float3x3 localToWorld = float3x3(bsdfData.tangentWS, bsdfData.bitangentWS, bsdfData.normalWS);
+    float3x3 localToWorld;
+
+    if (bsdfData.materialId == MATERIALID_LIT_ANISO)
+    {
+        localToWorld = float3x3(bsdfData.tangentWS, bsdfData.bitangentWS, bsdfData.normalWS);
+    }
+    else
+    {
+        // We do not have a tangent frame unless we use anisotropic GGX.
+        localToWorld = GetLocalFrame(bsdfData.normalWS);
+    }
+
     float    NdotV        = max(preLightData.NdotV, MIN_N_DOT_V);
     float3   acc          = float3(0.0, 0.0, 0.0);
 
         {
             ImportanceSampleGGX(u, V, localToWorld, bsdfData.roughness, NdotV, L, VdotH, NdotL, weightOverPdf);
         }
-
 
         if (NdotL > 0.0)
         {