Add slot type for bound types to be used in PBR Master node

com.unity.shadergraph/Editor/Data/Graphs/NormalMaterialSlot.cs

 using System;
 using UnityEditor.ShaderGraph.Drawing.Slots;
 using UnityEngine.Experimental.UIElements;
+using UnityEngine;
-    public class NormalMaterialSlot : SpaceMaterialSlot, IMayRequireNormal, IMayRequireTangent
+    public class NormalMaterialSlot : SpaceMaterialSlot, IMayRequireNormal
     {
         public NormalMaterialSlot()
         {}
         }
 
         public NeededCoordinateSpace RequiresNormal()
-        {
-            if (isConnected)
-                return NeededCoordinateSpace.None;
-            return space.ToNeededCoordinateSpace();
-        }
-        public NeededCoordinateSpace RequiresTangent()
         {
             if (isConnected)
                 return NeededCoordinateSpace.None;

com.unity.shadergraph/Editor/Data/MasterNodes/PBRMasterNode.cs

         {
             name = "PBR Master";
             AddSlot(new ColorRGBMaterialSlot(AlbedoSlotId, AlbedoSlotName, AlbedoSlotName, SlotType.Input, Color.grey, ShaderStage.Fragment));
-            AddSlot(new NormalMaterialSlot(NormalSlotId, NormalSlotName, NormalSlotName, CoordinateSpace.Tangent, ShaderStage.Fragment));
+            AddSlot(new BoundVector3MaterialSlot(NormalSlotId, NormalSlotName, NormalSlotName, new Vector3(0, 0, 1), CoordinateSpace.Tangent, ShaderStage.Fragment));
             AddSlot(new ColorRGBMaterialSlot(EmissionSlotId, EmissionSlotName, EmissionSlotName, SlotType.Input, Color.black, ShaderStage.Fragment));
             if (model == Model.Metallic)
                 AddSlot(new Vector1MaterialSlot(MetallicSlotId, MetallicSlotName, MetallicSlotName, SlotType.Input, 0, ShaderStage.Fragment));

com.unity.shadergraph/Editor/Data/Graphs/BoundVector3MaterialSlot.cs

+using System;
+using UnityEditor.Graphing;
+using UnityEditor.ShaderGraph.Drawing.Slots;
+using UnityEngine;
+using UnityEngine.Experimental.UIElements;
+
+namespace UnityEditor.ShaderGraph
+{
+    [Serializable]
+    public class BoundVector3MaterialSlot : SpaceMaterialSlot
+    {
+        [SerializeField]
+        private CoordinateSpace m_Space;
+
+        public BoundVector3MaterialSlot()
+        {
+        }
+
+        public BoundVector3MaterialSlot(
+            int slotId,
+            string displayName,
+            string shaderOutputName,
+            Vector3 value,
+            CoordinateSpace space,
+            ShaderStage shaderStage = ShaderStage.Dynamic,
+            bool hidden = false)
+            : base(slotId, displayName, shaderOutputName, space, shaderStage, hidden)
+        {
+            this.value = value;
+        }
+
+        public override VisualElement InstantiateControl()
+        {
+            return new BoundInputVectorControlView(space + " Space");
+        }
+
+        protected override string ConcreteSlotValueAsVariable(AbstractMaterialNode.OutputPrecision precision)
+        {
+            return precision + String.Format("3 ({0}, {1}, {2})", NodeUtils.FloatToShaderValue(value.x), NodeUtils.FloatToShaderValue(value.y), NodeUtils.FloatToShaderValue(value.z));
+        }
+
+        public override void CopyValuesFrom(MaterialSlot foundSlot)
+        {
+            var slot = foundSlot as BoundVector3MaterialSlot;
+            if (slot != null)
+                value = slot.value;
+        }
+    }
+}

com.unity.shadergraph/Editor/Data/Graphs/BoundVector3MaterialSlot.cs.meta

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