Provide a mechanism for naming a hash table so that it can be used in DumpStats to identify the tab…

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index 3581662c14f696f979b44ba1988a2f582f1766d9..407d688631db6cd7f12a2ee09f3b9545d6a15307 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -11980,6 +11980,8 @@ struct ConstantPosKey : ValueObject {
 
 class ConstMapKeyEqualsTraits {
  public:
+  static const char* Name() { return "ConstMapKeyEqualsTraits"; }
+
   static bool IsMatch(const Object& a, const Object& b) {
     const Array& key1 = Array::Cast(a);
     const Array& key2 = Array::Cast(b);