Fix scroll position being incorrect

Fixes bugs related to scroll position when the webView sits underneath the nav bar due to how the contentInsets are applied.

Author: zachwaugh

Turbolinks/VisitableView.swift

@@ -32,7 +32,6 @@ open class VisitableView: UIView {
         self.visitable = visitable
         addSubview(webView)
         addFillConstraints(forView: webView)
-        updateContentInsets()
         installRefreshControl()
         showOrHideWebView()
     }
@@ -199,7 +198,11 @@ open class VisitableView: UIView {
     }
 
     private func updateContentInsets() {
-        updateWebViewScrollViewInsets(contentInset ?? hiddenScrollView.contentInset)
+        if #available(iOS 11, *) {
+            updateWebViewScrollViewInsets(contentInset ?? hiddenScrollView.adjustedContentInset)
+        } else {
+            updateWebViewScrollViewInsets(contentInset ?? hiddenScrollView.contentInset)
+        }
     }
 
     private func addFillConstraints(forView view: UIView) {

Turbolinks/WebView.swift

@@ -36,6 +36,10 @@ class WebView: WKWebView {
 
         translatesAutoresizingMaskIntoConstraints = false
         scrollView.decelerationRate = UIScrollViewDecelerationRateNormal
+        
+        if #available(iOS 11, *) {
+            scrollView.contentInsetAdjustmentBehavior = .never
+        }
     }
 
     required init?(coder: NSCoder) {

TurbolinksDemo/ApplicationController.swift

@@ -26,6 +26,10 @@ class ApplicationController: UINavigationController {
 
     override func viewDidLoad() {
         super.viewDidLoad()
+        
+        // Switching this to false will prevent content from sitting beneath scrollbar
+        navigationBar.isTranslucent = true
+        
         presentVisitableForSession(session, url: url)
     }