HLSL: Implement 'this' keyword.

Test/hlsl.this.frag

@@ -0,0 +1,29 @@
+static float2 var = float2(1.0, 2.0);
+
+struct type1
+{
+    int memFun1(int3 var)
+    {
+        return var.z + this.var + var2;
+    }
+    int memFun2(int a)
+    {
+        int3 var = int3(1,2,3);
+        return var.z + (int)bar.y + this.var2;
+    }
+    float2 bar;
+    int var;
+    int var2;
+};
+
+float4 main() : SV_Target0
+{
+   type1 T;
+   T.bar = var;
+   T.var = 7;
+   T.var2 = 9;
+   int i = T.memFun1(int3(10,11,12));
+   i += T.memFun2(17);
+
+   return float4(i,i,i,i);
+}