HLSL: phase 2d: minor cleanup, & allow operator[] on non-rw textures

Improve comments.
A few tweaked lines allow [] on non-rw tx.  Add test case for this.
Improve VectorTimesScalar handling.

Test/hlsl.tx.bracket.frag

@@ -0,0 +1,73 @@
+SamplerState       g_sSamp : register(s0);
+
+Texture1D <float4> g_tTex1df4 : register(t0);
+Texture1D <int4>   g_tTex1di4;
+Texture1D <uint4>  g_tTex1du4;
+
+Texture2D <float4> g_tTex2df4;
+Texture2D <int4>   g_tTex2di4;
+Texture2D <uint4>  g_tTex2du4;
+
+Texture3D <float4> g_tTex3df4;
+Texture3D <int4>   g_tTex3di4;
+Texture3D <uint4>  g_tTex3du4;
+
+Texture1DArray <float4> g_tTex1df4a;
+Texture1DArray <int4>   g_tTex1di4a;
+Texture1DArray <uint4>  g_tTex1du4a;
+
+Texture2DArray <float4> g_tTex2df4a;
+Texture2DArray <int4>   g_tTex2di4a;
+Texture2DArray <uint4>  g_tTex2du4a;
+
+struct PS_OUTPUT
+{
+    float4 Color : SV_Target0;
+};
+
+uniform int   c1;
+uniform int2  c2;
+uniform int3  c3;
+uniform int4  c4;
+
+uniform int   o1;
+uniform int2  o2;
+uniform int3  o3;
+uniform int4  o4;
+
+int4   Fn1(in int4 x)   { return x; }
+uint4  Fn1(in uint4 x)  { return x; }
+float4 Fn1(in float4 x) { return x; }
+
+float4 SomeValue() { return c4; }
+
+PS_OUTPUT main()
+{
+   PS_OUTPUT psout;
+
+   // 1D
+   g_tTex1df4[c1];
+   
+   float4 r00 = g_tTex1df4[c1];
+   int4   r01 = g_tTex1di4[c1];
+   uint4  r02 = g_tTex1du4[c1];
+
+   // 2D
+   float4 r10 = g_tTex2df4[c2];
+   int4   r11 = g_tTex2di4[c2];
+   uint4  r12 = g_tTex2du4[c2];
+   
+   // 3D
+   float4 r20 = g_tTex3df4[c3];
+   int4   r21 = g_tTex3di4[c3];
+   uint4  r22 = g_tTex3du4[c3];
+
+   // Test function calling
+   Fn1(g_tTex1df4[c1]);  // in
+   Fn1(g_tTex1di4[c1]);  // in
+   Fn1(g_tTex1du4[c1]);  // in
+
+   psout.Color = 1.0;
+
+   return psout;
+}