writer/wgsl: Emit atomic types

Bug: tint:892
Change-Id: Ie483167bcf669e5f2d6b5489a915584fc3678183
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/54649
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: David Neto <dneto@google.com>
diff --git a/test/intrinsics/gen/atomicMin/c67a74.wgsl.expected.msl b/test/intrinsics/gen/atomicMin/c67a74.wgsl.expected.msl
index 28d463e..1b28fe8 100644
--- a/test/intrinsics/gen/atomicMin/c67a74.wgsl.expected.msl
+++ b/test/intrinsics/gen/atomicMin/c67a74.wgsl.expected.msl
@@ -3,5 +3,23 @@
 
 [[block]]
 struct SB_RW {
-  arg_0 : 
+  arg_0 : atomic<u32>;
+};
+
+[[group(0), binding(0)]] var<storage, read_write> sb_rw : SB_RW;
+
+fn atomicMin_c67a74() {
+  var res : u32 = atomicMin(&(sb_rw.arg_0), 1u);
+}
+
+[[stage(fragment)]]
+fn fragment_main() {
+  atomicMin_c67a74();
+}
+
+[[stage(compute)]]
+fn compute_main() {
+  atomicMin_c67a74();
+}
+
 Failed to generate: error: unknown type in EmitType: __atomic__u32