[vm] Remove unused Library::CloneMetadataFrom() function

TEST=Removal of unused code.

Change-Id: Ia5bb3d8e4b8aec8948d5dee8e15b6e014ce3327f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/172600
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>

runtime/vm/object.cc

@@ -11740,18 +11740,6 @@ FieldPtr Library::GetMetadataField(const String& metaname) const {
   return Field::null();
 }
 
-void Library::CloneMetadataFrom(const Library& from_library,
-                                const Function& from_fun,
-                                const Function& to_fun) const {
-  const String& metaname = String::Handle(MakeMetadataName(from_fun));
-  const Field& from_field =
-      Field::Handle(from_library.GetMetadataField(metaname));
-  if (!from_field.IsNull()) {
-    AddFunctionMetadata(to_fun, from_field.token_pos(),
-                        from_field.kernel_offset());
-  }
-}
-
 ObjectPtr Library::GetMetadata(const Object& obj) const {
 #if defined(DART_PRECOMPILED_RUNTIME)
   return Object::empty_array().raw();

runtime/vm/object.h

@@ -4709,9 +4709,6 @@ class Library : public Object {
                           intptr_t kernel_offset) const;
   void AddTypeParameterMetadata(const TypeParameter& param,
                                 TokenPosition token_pos) const;
-  void CloneMetadataFrom(const Library& from_library,
-                         const Function& from_fun,
-                         const Function& to_fun) const;
   ObjectPtr GetMetadata(const Object& obj) const;
 
   // Tries to finds a @pragma annotation on [object].