[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/src/tint/lang/core/texel_format.cc b/src/tint/lang/core/texel_format.cc
index c0f552a..1371c35 100644
--- a/src/tint/lang/core/texel_format.cc
+++ b/src/tint/lang/core/texel_format.cc
@@ -54,6 +54,9 @@
     if (str == "r32uint") {
         return TexelFormat::kR32Uint;
     }
+    if (str == "r8unorm") {
+        return TexelFormat::kR8Unorm;
+    }
     if (str == "rg32float") {
         return TexelFormat::kRg32Float;
     }
@@ -108,6 +111,8 @@
             return "r32sint";
         case TexelFormat::kR32Uint:
             return "r32uint";
+        case TexelFormat::kR8Unorm:
+            return "r8unorm";
         case TexelFormat::kRg32Float:
             return "rg32float";
         case TexelFormat::kRg32Sint: