tint/uniformity: Fix debug graph output

The code that was ifdef'd out no longer compiled.

Change-Id: I6243cc6a3584c555505c4bee68ec02bbb96801c3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/113430
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: James Price <jrprice@google.com>
diff --git a/src/tint/resolver/uniformity.cc b/src/tint/resolver/uniformity.cc
index 30dd30f..491360f 100644
--- a/src/tint/resolver/uniformity.cc
+++ b/src/tint/resolver/uniformity.cc
@@ -249,10 +249,10 @@
         // This only matters if we're dumping the graph.
         std::string unique_tag = tag;
         int suffix = 0;
-        while (tags_.count(unique_tag)) {
+        while (tags_.Contains(unique_tag)) {
             unique_tag = tag + "_$" + std::to_string(++suffix);
         }
-        tags_.insert(unique_tag);
+        tags_.Add(unique_tag);
         node->tag = name + "." + unique_tag;
 #endif