Fixed rendering when no lights we present in the scene. Updated test scenes and images.

Assets/GraphicsTests/RenderPipeline/LightweightPipeline/Scenes/MultiplePointLights.unity

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Assets/GraphicsTests/RenderPipeline/LightweightPipeline/Scenes/Shaders/LDPipe_LitShaderMaps.unity

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Assets/ScriptableRenderPipeline/LightweightPipeline.meta

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+guid: 4923a4700d4d643a9a862a74e04870b3
 folderAsset: yes
 timeCreated: 1481548458
 licenseType: Pro

Assets/ScriptableRenderPipeline/LightweightPipeline/LightweightPipeline.cs

             lightData.pixelLightsCount = Mathf.Min(lightsCount, m_Asset.MaxSupportedPixelLights);
             lightData.vertexLightsCount = (m_Asset.SupportsVertexLight) ? Mathf.Min(lightsCount - lightData.pixelLightsCount, kMaxVertexLights) : 0;
             lightData.isSingleDirectionalLight = lightData.pixelLightsCount == 1 && lightData.vertexLightsCount == 0 && lights[0].lightType == LightType.Directional;
+
+            // Directional light path can handle unlit.
+            if (lightsCount == 0)
+                lightData.isSingleDirectionalLight = true;
+            
             lightData.shadowsRendered = false;
 
             InitializeMainShadowLightIndex(lights, out lightData.shadowLightIndex);
 
         private void SetupShaderLightConstants(VisibleLight[] lights, ref LightData lightData, ref CullResults cullResults, ref ScriptableRenderContext context)
         {
+            if (lights.Length == 0)
+                return;
+
             if (lightData.isSingleDirectionalLight) 
                 SetupShaderSingleDirectionalLightConstants(ref lights [0], ref context);
             else