Fix errors and warnings

pkg/analyzer/lib/src/kernel/ast_from_analyzer.dart

 // Copyright (c) 2016, 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 kernel.analyzer.ast_from_analyzer;
 
 import 'package:kernel/ast.dart' as ast;
 import 'package:kernel/frontend/accessors.dart';
 import 'package:kernel/frontend/super_initializers.dart';
 import 'package:kernel/log.dart';
 import 'package:kernel/type_algebra.dart';
@@ skipping 2510 matching lines @@
         }
       }
     }
 
     if (!foundConstructor) {
       var defaultConstructor = scope.findDefaultConstructor(node.element);
       if (defaultConstructor != null) {
         assert(defaultConstructor.enclosingElement == node.element);
         if (!defaultConstructor.isSynthetic) {
           throw 'Non-synthetic default constructor not in list of members. '
-              '${node} $element $defaultConstructor';
+              '$node $element $defaultConstructor';
         }
         var memberNode = scope.getMemberReference(defaultConstructor);
         classNode.addMember(memberNode);
         buildDefaultConstructor(memberNode, defaultConstructor);
       }
     }
 
     addDefaultInstanceFieldInitializers(classNode);
   }
 
@@ skipping 530 matching lines @@
     if (list[i - 1].compareTo(item) == 0) {
       ++deleted;
     } else if (deleted > 0) {
       list[i - deleted] = item;
     }
   }
   if (deleted > 0) {
     list.length -= deleted;
   }
 }