Fix build: Add 'ReferenceKind.length' to the switch.

pkg/analyzer/lib/src/summary/resynthesize.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 summary_resynthesizer;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
@@ skipping 626 matching lines @@
         return new FunctionTypeAliasElementHandle(
             summaryResynthesizer, location);
       case ReferenceKind.topLevelFunction:
         return new FunctionElementHandle(summaryResynthesizer, location);
       case ReferenceKind.topLevelPropertyAccessor:
         return new PropertyAccessorElementHandle(
             summaryResynthesizer, location);
       case ReferenceKind.constructor:
       case ReferenceKind.constField:
       case ReferenceKind.staticMethod:
+      case ReferenceKind.length:
       case ReferenceKind.prefix:
       case ReferenceKind.unresolved:
         // Should never happen.  Exported names never refer to import prefixes,
         // and they always refer to defined top-level entities.
         throw new StateError('Unexpected export name kind: ${exportName.kind}');
     }
   }
 
   /**
    * Build the export namespace for the library by aggregating together its
@@ skipping 559 matching lines @@
     for (PropertyAccessorElementImpl accessor in unit.accessors) {
       elementMap[accessor.identifier] = accessor;
     }
     resummarizedElements[absoluteUri] = elementMap;
     unitHolder = null;
     linkedUnit = null;
     unlinkedUnit = null;
     linkedTypeMap = null;
   }
 }