Fix closure compiler errors which are introduced by 931603002.

ui/file_manager/file_manager/foreground/js/directory_contents.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Scanner of the entries.
  * @constructor
  */
 function ContentScanner() {
   this.cancelled_ = false;
@@ skipping 668 matching lines @@
     this.fileList_ = new cr.ui.ArrayDataModel(fileList);
   this.makeSpaceInMetadataCache_(this.fileList_.length);
 };
 
 /**
  * Creates snapshot of metadata in the directory.
  * @return {!Object} Metadata snapshot of current directory contents.
  */
 DirectoryContents.prototype.createMetadataSnapshot = function() {
   var snapshot = {};
-  var entries = this.fileList_.slice();
+  var entries = /** @type {!Array<!Entry>} */ (this.fileList_.slice());
   var metadata = this.context_.fileSystemMetadata.getCache(
       entries, ['modificationTime']);
   for (var i = 0; i < entries.length; i++) {
     snapshot[entries[i].toURL()] = metadata[i];
   }
   return snapshot;
 }
 
 /**
  * Sets metadata snapshot which is used to check changed files.
@@ skipping 17 matching lines @@
     var spliceArgs = this.fileList_.slice();
     var fileList = this.context_.fileList;
     spliceArgs.unshift(0, fileList.length);
     fileList.splice.apply(fileList, spliceArgs);
     this.fileList_ = fileList;
     this.makeSpaceInMetadataCache_(this.fileList_.length);
 
     // Check updated files and dispatch change events.
     if (this.metadataSnapshot_) {
       var updatedIndexes = [];
-      var entries = this.fileList_.slice();
+      var entries = /** @type {!Array<!Entry>} */ (this.fileList_.slice());
       var newMetadatas = this.context_.fileSystemMetadata.getCache(
           entries, ['modificationTime']);
 
       for (var i = 0; i < entries.length; i++) {
         var url = entries[i].toURL();
         var newMetadata = newMetadatas[i];
         if (this.metadataSnapshot_[url] &&
             this.metadataSnapshot_[url].modificationTime &&
             this.metadataSnapshot_[url].modificationTime.getTime() !==
             newMetadata.modificationTime.getTime())
@@ skipping 361 matching lines @@
 DirectoryContents.createForDriveMetadataSearch = function(
     context, fakeDirectoryEntry, searchType) {
   return new DirectoryContents(
       context,
       true,  // Search
       fakeDirectoryEntry,
       function() {
         return new DriveMetadataSearchContentScanner(searchType);
       });
 };