Inline javascript:'' within NamedFrame's internal SafeHtmlTemplate

This prevents the URI from being sanitized by the SafeHtmlTemplates
generator. This is a regression from GWT 2.4, introduced at r10801.

Fixes issue 7909

Change-Id: Ic96c36b3f98705fff8a7638c8975901c50856951
Review-Link: https://gwt-review.googlesource.com/#/c/1800/

Review by: goktug@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@11473 8db76d5a-ed1c-0410-87a9-c151d255dfc7