[rb] explicitly check for whether driver supports full page screenshots to error (#12799)

Author: titusfortner

rb/lib/selenium/webdriver/common/takes_screenshot.rb

@@ -49,6 +49,10 @@ def save_screenshot(png_path, full_page: false)
       # @api public
 
       def screenshot_as(format, full_page: false)
+        if full_page && !respond_to(:full_page)
+          raise Error::UnsupportedOperationError, "Full Page Screenshots are not supported for #{inspect}"
+        end
+
         case format
         when :base64
           full_page ? full_screenshot : screenshot
@@ -57,8 +61,6 @@ def screenshot_as(format, full_page: false)
         else
           raise Error::UnsupportedOperationError, "unsupported format: #{format.inspect}"
         end
-      rescue NameError
-        raise Error::UnsupportedOperationError, "Full Page Screenshots are not supported for #{inspect}"
       end
     end # TakesScreenshot
   end # WebDriver