Added "load stale" IDS grit variables to IOS whitelist.

Needed for http://codereview.chromium.org/207553008 (r264696) to 
build on IOS.

BUG=329621
R=rohitrao@chromium.org

Review URL: https://codereview.chromium.org/244463003

git-svn-id: http://src.chromium.org/svn/trunk/src/build@264963 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

ios/grit_whitelist.txt

@@ -259,6 +259,8 @@ IDS_EMPTY_KEYWORD_VALUE
 IDS_ENABLE_BACKLOADER_DESCRIPTION
 IDS_ENABLE_BACKLOADER_NAME
 IDS_ERRORPAGES_BUTTON_LESS
+IDS_ERRORPAGES_BUTTON_LOAD_STALE
+IDS_ERRORPAGES_BUTTON_LOAD_STALE_HELP
 IDS_ERRORPAGES_BUTTON_MORE
 IDS_ERRORPAGES_BUTTON_RELOAD
 IDS_ERRORPAGES_DETAILS_ADDRESS_UNREACHABLE