AAPT2: Fix Plural::Equals() method

Test: make aapt2_tests
Bug: 35902437
Change-Id: I8797f89af58876f891f0b0c5cce85fd7781c4e24
diff --git a/tools/aapt2/optimize/ResourceDeduper.cpp b/tools/aapt2/optimize/ResourceDeduper.cpp
index 3aab2e3..9d16268 100644
--- a/tools/aapt2/optimize/ResourceDeduper.cpp
+++ b/tools/aapt2/optimize/ResourceDeduper.cpp
@@ -77,6 +77,8 @@
           DiagMessage(node_value->value->GetSource())
           << "removing dominated duplicate resource with name \""
           << entry_->name << "\"");
+      context_->GetDiagnostics()->Note(
+          DiagMessage(parent_value->value->GetSource()) << "dominated here");
     }
     node_value->value = {};
   }