Configure iOS Gmail.app to open links in Safari.app (not internal browser)?

I have Safari set as my "Browser" in "Default Apps" in Gmail.app's "Settings". When I open a link in Gmail, it opens an internal browser instead of the Safari.app. How can I configure the links to open in the Safari.app itself where I'm already signed into various services etc? Gmail.app "Settings" does not have any options related to this. When setting the "Default Apps > Browser" to Chrome, it opens Chrome.app as desired - but I want to use Safari.app.