[dart2js] Fix finalization bug in namer_names.dart

Change-Id: I8ad37e67bfee2b8fb022fcffedee74c4c6b19b6d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/192043
Reviewed-by: Stephen Adams <[email protected]>
Commit-Queue: Joshua Litt <[email protected]>

Author: joshualitt

pkg/compiler/lib/src/js_backend/namer_names.dart

@@ -145,6 +145,9 @@ class CompoundName extends _NamerName implements jsAst.AstContainer {
 
   CompoundName.from(List<jsAst.Name> parts) : this(<_NamerName>[...parts]);
 
+  @override
+  bool get isFinalized => _parts.every((name) => name.isFinalized);
+
   @override
   String get name {
     if (_cachedName == null) {