Enable FF6 Plugin in MissingPlugin Page.

Review at http://gwt-code-reviews.appspot.com/1551803

Review by: rjrjr@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10663 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/plugins/MissingPlugin/war/MissingPlugin.html b/plugins/MissingPlugin/war/MissingPlugin.html
index 8f1e33a..43756ec 100644
--- a/plugins/MissingPlugin/war/MissingPlugin.html
+++ b/plugins/MissingPlugin/war/MissingPlugin.html
@@ -35,7 +35,7 @@
 
           "firefox-old" :
           {
-            "caption" : "Sorry, the GWT Developer Plugin only supports Firefox 3.0 - 5.0 at present",
+            "caption" : "Sorry, the GWT Developer Plugin only supports Firefox 3.0 - 6.0 at present",
             "url" : "http://www.getfirefox.com",
             "supported" : false
           },
@@ -173,7 +173,8 @@
       } else if (ua.indexOf("gecko") != -1) {
       if (ua.indexOf("rv:1.9") != -1 ||
           ua.indexOf("rv:2.0") != -1 ||
-          ua.indexOf("rv:5.0") != -1) {
+          ua.indexOf("rv:5.0") != -1 ||
+          ua.indexOf("rv:6.0") != -1) {
           id = 'firefox';
         } else {
           id = 'firefox-old';