title: WKWebView content jumping on load
body: <p>I've created a simple test app to reproduce my problem reliably and minimize the moving parts. It contains just a navigation controller and a view controller that I add a WKWebView to. I immediately tell that WKWebView to navigate to <a href="http://www.google.ca" rel="noreferrer">www.google.ca</a>. Once the page has loaded, the content automatically jumps up underneath the header bar. This is reproducible consistently on various simulators/devices running iOS 8/9/9.1. Below is the code for my ViewController:</p>
  
  <pre><code>//  ViewController.swift
  import UIKit
  import WebKit
  
  class ViewController: UIViewController {
      let webView = WKWebView()
  
      override func viewDidLoad() {
          super.viewDidLoad()
          view.addSubview(webView)
          let url = NSURL(string: "http://www.google.ca")!
          let request = NSURLRequest(URL: url)
          webView.loadRequest(request)
          webView.frame = view.bounds
      }
  }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/dowcL.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/dowcL.gif" alt="GIF"></a></p>