[Jeehut]

Overview

WebView called webView.load(…) in every updateUIView/updateNSView, i.e. on every state change of the surrounding view. That reset the page the user had navigated to and the scroll position. The coordinator now remembers the loaded URL and loads only when it changed. It also updates parent, so a new onOpenExternalURL closure takes effect.

Split out of #7.

How this was verified

WebViewTests call the representable's real update(_:coordinator:) with a WKWebView subclass that records load requests. Three updates with the same URL load once; a URL change loads the new URL once and updates the coordinator's parent.

main has no update(_:coordinator:), so for the red run the URL check was removed, which is main's behavior (always load):

✘ repeatedUpdatesLoadTheURLOnlyOnce(): webView.loadedURLs == [self.pageURL]
✘ updateWithChangedURLLoadsTheNewURL(): webView.loadedURLs == [self.pageURL, self.otherPageURL]
✘ Test run with 2 tests in 1 suite failed with 2 issues.

Green, this branch:

✔ Test run with 2 tests in 1 suite passed.