fix #27421, DDC did not generate implicit super calls in some cases

pkg/dev_compiler/lib/src/compiler/code_generator.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:collection' show HashMap, HashSet;
 import 'dart:math' show min, max;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1866 matching lines @@
     }
     return members;
   }
 
   /// Generates the implicit default constructor for class C of the form
   /// `C() : super() {}`.
   JS.Method _emitImplicitConstructor(
       ClassDeclaration node,
       List<FieldDeclaration> fields,
       Map<FieldElement, JS.TemporaryId> virtualFields) {
-    assert(_hasUnnamedConstructor(node.element) == fields.isNotEmpty);
-
     // If we don't have a method body, skip this.
     var superCall = _superConstructorCall(node.element);
     if (fields.isEmpty && superCall == null) return null;
 
     var initFields = _initializeFields(node, fields, virtualFields);
     List<JS.Statement> body = [initFields];
     if (superCall != null) {
       body.add(superCall);
     }
     var name = _constructorName(node.element.unnamedConstructor);
@@ skipping 153 matching lines @@
     }
 
     if (superCtor == null) {
       // This will only happen if the code has errors:
       // we're trying to generate an implicit constructor for a type where
       // we don't have a default constructor in the supertype.
       assert(options.unsafeForceCompile);
       return null;
     }
 
-    if (superCtor.name == '' && !_shouldCallUnnamedSuperCtor(element)) {
+    if (superCtor.name == '' && !_hasUnnamedSuperConstructor(element)) {
       return null;
     }
 
     var name = _constructorName(superCtor);
     var args = node != null ? _visit(node.argumentList) : [];
     return annotate(js.statement('super.#(#);', [name, args]), node);
   }
 
-  bool _shouldCallUnnamedSuperCtor(ClassElement e) {
+  bool _hasUnnamedSuperConstructor(ClassElement e) {
     var supertype = e.supertype;
     if (supertype == null) return false;
     if (_hasUnnamedConstructor(supertype.element)) return true;
     for (var mixin in e.mixins) {
       if (_hasUnnamedConstructor(mixin.element)) return true;
     }
     return false;
   }
 
   bool _hasUnnamedConstructor(ClassElement e) {
     if (e.type.isObject) return false;
     if (!e.unnamedConstructor.isSynthetic) return true;
-    return e.fields.any((f) => !f.isStatic && !f.isSynthetic);
+    if (e.fields.any((f) => !f.isStatic && !f.isSynthetic)) return true;
+    return _hasUnnamedSuperConstructor(e);
   }
 
   /// Initialize fields. They follow the sequence:
   ///
   ///   1. field declaration initializer if non-const,
   ///   2. field initializing parameters,
   ///   3. constructor field initializers,
   ///   4. initialize fields not covered in 1-3
   JS.Statement _initializeFields(
       ClassDeclaration cls,
@@ skipping 3393 matching lines @@
 }
 
 bool isLibraryPrefix(Expression node) =>
     node is SimpleIdentifier && node.staticElement is PrefixElement;
 
 LibraryElement _getLibrary(AnalysisContext c, String uri) =>
     c.computeLibraryElement(c.sourceFactory.forUri(uri));
 
 bool _isDartRuntime(LibraryElement l) =>
     l.isInSdk && l.source.uri.toString() == 'dart:_runtime';