Closing empty tabs after download

[tomasstrba]

Task/Issue URL: https://app.asana.com/0/1177771139624306/1206835038894671/f

Description:
Fix of empty tabs remaining in the tab bar after a download finishes.

Steps to test this PR:
Test downloads which open a new tab are closed

1. Visit this task
2. Click on the download icon on the first image
3. Make sure the new tab is closed after download finishes
4. Click on the same image again
5. Make sure the new tab is closed after download finishes

Test downloads which doesn't open a new tab

1. Visit this task
2. Click on the image to start the download
3. Make sure the current tab is not closed

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Internal references:

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[mallexxx]

@tomasstrba, unfortunately this is not a completely correct implementation: we‘re trying to close the web view for any navigation response (navAction == nil) converted to download, the web view won‘t close here only because it wasn‘t created by js (you can see the error message in js console)

I suggest the following change:

        var isMainFrameNavigationActionWithNoHistory: Bool {
            guard let navigationAction,
                  navigationAction.isForMainFrame,
                  navigationAction.isTargetingNewWindow,
                  // webView has no navigation history (downloaded navigationAction has started from an empty state)
                  (navigationAction.redirectHistory?.first ?? navigationAction).fromHistoryItemIdentity == nil
            else { return false }
            return true
        }
        guard let webView = download.webView,
              isMainFrameNavigationActionWithNoHistory
                // if converted from navigation response but no page was loaded
                || navigationAction == nil && webView.backForwardList.currentItem == nil else { return }

[tomasstrba]

Thank you, @mallexxx! Unfortunately, this solution doesn't work for this scenario:

1. Open https://app.asana.com/0/1142021229838617/1206919179674977/f
2. Repeatedly download images using the download button

[mallexxx]

There was an unintended code duplication, I‘ve fixed it,
Validated the tests steps: LGTM

[tomasstrba]

I tested it too and it works as expected 💯 Thank you for the better fix, @mallexxx!