How to get HTML of DOM element in Capybara?

I want to debug/develop code using irb:

irb> require "capybara"
irb> include Capybara::DSL
irb> Capybara.current_driver = :selenium
irb> visit "http://example.com"

But how do I get an HTML of the element I found?

irb> s = find(".user-pane")
=> #<Capybara::Element tag="nav">
irb> s.native.inner_html
NoMethodError: undefined method `inner_html' for #<Selenium::WebDriver::Element:0x007fc1da191b28>

gem list

capybara (2.4.4)
nokogiri (1.5.6)
selenium-webdriver (2.43.0)

Solutions, that I've found on SO and elsewhere don't work:

• Why .inner_html doesn't work anymore?
  Because .native is now WebDriver, not Nokogiri object.
• Why .native.get_attribute doesn't work?
  Because the method has the name different from Python.

So the answer is: s.native.attribute('outerHTML')
But it takes near 5 second to accomplish even on google.com page.

UPD: .property("outerHTML") if Cuprite, not Selenium.