[tint] Implement support for r8unorm

Bug: dawn:2101
Change-Id: I0ebb48c577f114efd9e2564ac818c4869852a927
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/176042
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/test/tint/builtins/gen/literal/textureLoad/5dd4c7.wgsl.expected.dxc.hlsl b/test/tint/builtins/gen/literal/textureLoad/5dd4c7.wgsl.expected.dxc.hlsl
new file mode 100644
index 0000000..3942020
--- /dev/null
+++ b/test/tint/builtins/gen/literal/textureLoad/5dd4c7.wgsl.expected.dxc.hlsl
@@ -0,0 +1,34 @@
+Texture2D<float4> arg_0 : register(t0, space1);
+RWByteAddressBuffer prevent_dce : register(u0, space2);
+
+void textureLoad_5dd4c7() {
+  float4 res = arg_0.Load(int3((1).xx, 0));
+  prevent_dce.Store4(0u, asuint(res));
+}
+
+struct tint_symbol {
+  float4 value : SV_Position;
+};
+
+float4 vertex_main_inner() {
+  textureLoad_5dd4c7();
+  return (0.0f).xxxx;
+}
+
+tint_symbol vertex_main() {
+  float4 inner_result = vertex_main_inner();
+  tint_symbol wrapper_result = (tint_symbol)0;
+  wrapper_result.value = inner_result;
+  return wrapper_result;
+}
+
+void fragment_main() {
+  textureLoad_5dd4c7();
+  return;
+}
+
+[numthreads(1, 1, 1)]
+void compute_main() {
+  textureLoad_5dd4c7();
+  return;
+}