Cleanup unused Dart API Dart_IdentityHash

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index 6cbebeba35caf6534cc70351f082e0d36edd98f9..ab15af12bf8084baaa25ab367840eac1c3c4c568 100644
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -434,17 +434,6 @@ DART_EXPORT Dart_Handle Dart_ToString(Dart_Handle object);
  */
 DART_EXPORT bool Dart_IdentityEquals(Dart_Handle obj1, Dart_Handle obj2);
 
-/**
- * Returns a hash code for the argument. The hash code of objects that are equal
- * according to Dart_IdentityEquals will return the same hash code, but the hash
- * codes of non-equal objects are not necessarily distinct.
- *
- * \param obj An object for which to derive a hash code.
- *
- * \return A hash code for the parameter.
- */
-DART_EXPORT uint64_t Dart_IdentityHash(Dart_Handle obj);
-
 /**
  * Allocates a handle in the current scope from a persistent handle.
  */