Invalidate resolution if a unit instantiate a class with the unnamed constructor change.

pkg/analyzer/lib/src/task/incremental_element_builder.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.
 
 library analyzer.src.task.incremental_element_builder;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 16 matching lines @@
 
   final Set<ClassElementDelta> superDeltas = new Set<ClassElementDelta>();
 
   final List<PropertyAccessorElement> addedAccessors =
       <PropertyAccessorElement>[];
   final List<PropertyAccessorElement> removedAccessors =
       <PropertyAccessorElement>[];
 
   final List<ConstructorElement> addedConstructors = <ConstructorElement>[];
   final List<ConstructorElement> removedConstructors = <ConstructorElement>[];
+  bool hasUnnamedConstructorChange = false;
 
   final List<MethodElement> addedMethods = <MethodElement>[];
   final List<MethodElement> removedMethods = <MethodElement>[];
 
   ClassElementDelta(this._element, this.librarySource, this.name);
 
   /**
    * Return `true` if this delta has changes to the [name] visible in the
    * given [librarySource].
    */
@@ skipping 290 matching lines @@
     classElement.fields = newFields.values.toList();
     classElement.methods = classElementHolder.methods;
     classElement.version++;
     classElementHolder.validate();
     // Ensure at least a default synthetic constructor.
     if (classElement.constructors.isEmpty) {
       ConstructorElementImpl constructor =
           new ConstructorElementImpl.forNode(null);
       constructor.synthetic = true;
       classElement.constructors = <ConstructorElement>[constructor];
+      classDelta.addedConstructors.add(constructor);
     }
+    classDelta.hasUnnamedConstructorChange =
+        classDelta.addedConstructors.any((c) => c.name == '') ||
+            classDelta.removedConstructors.any((c) => c.name == '');
     // OK
     return classDelta;
   }
 
   void _processDirectives() {
     Map<String, Directive> oldDirectiveMap = new HashMap<String, Directive>();
     for (Directive oldDirective in oldUnit.directives) {
       String code = TokenUtils.getFullCode(oldDirective);
       oldDirectiveMap[code] = oldDirective;
     }
@@ skipping 339 matching lines @@
       }
     }
     super.visitElement(element);
   }
 
   static bool _isVariableInitializer(Element element) {
     return element is FunctionElement &&
         element.enclosingElement is VariableElement;
   }
 }