Disables context menu for LoginHtmlDialog.
Disables context menu for LoginHtmlDialog.

This dialog is used in the login time (e.g. Proxy preferences window).

BUG=chromium-os:7055
TEST=On the welcome screen click on 'Change proxy settings'. Notice that
context menu is disable in the opened Html viewer.

Review URL: http://codereview.chromium.org/3462020

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@60775 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser