Fix typo in files app

Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I57846f1fa7a86e58ed810363c63a723441b46cd0
Reviewed-on: https://chromium-review.googlesource.com/994932Reviewed-by: Naoki Fukino <fukino@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#548021}

ui/file_manager/file_manager/foreground/elements/files_metadata_entry.js

@@ -8,18 +8,18 @@ var FilesMetadataBox = Polymer({
   properties: {
     key: {
       type: String,
-      reflectToAttribtue: true,
+      reflectToAttribute: true,
     },
 
     // If |value| is empty, the entire entry will be hidden.
     value: {
       type: String,
-      reflectToAttribtue: true,
+      reflectToAttribute: true,
     },
 
     loading: {
       type: Boolean,
-      reflectToAttribtue: true,
+      reflectToAttribute: true,
       value: false,
     },
   },