[Tizen][Runtime] Enable to open navigation link in system web browser
when it's blocked by CSP mode.

On Tizen platform, the allow-navigation policy will control the behavior
for opening a navigation link in web app, if the navigation link domain
is not list in it, the action will be blocked and the link should be
opened in system web browser.

The patch does some reworks, since there are some issues when using the method
ContentBrowserClient::CanCommitURL, if it returns false, the render process
will be killed, and web application will crash, and it will be fixed in
this patch.
Merge pull request #1828 from takethathe/allow-navigation

[Tizen][Runtime] Enable to open navigation link in system web browser when it's blocked by CSP mode.