validation: atomics access mode and storage class

Bug: tint:901 tint:909
Change-Id: Ibbcdd80ddbe2aa9940bbd73bb404349afc633836
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/60080
Auto-Submit: Sarah Mashayekhi <sarahmashay@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Sarah Mashayekhi <sarahmashay@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/src/resolver/storage_class_validation_test.cc b/src/resolver/storage_class_validation_test.cc
index 89fa428..9a60ac4 100644
--- a/src/resolver/storage_class_validation_test.cc
+++ b/src/resolver/storage_class_validation_test.cc
@@ -108,7 +108,7 @@
 
   EXPECT_EQ(
       r()->error(),
-      R"(56:78 error: variables not in <storage> storage class must not declare an access mode)");
+      R"(56:78 error: only variables in <storage> storage class may declare an access mode)");
 }
 
 TEST_F(ResolverStorageClassValidationTest, StorageBufferNoBlockDecoration) {