Decide policy on load error

# Decide policy on load error

## Errors like WebKitErrorDomain (error code 102) and others interrupt the navigation process. In such cases navigation decisions should be made rather than rejected.

### It would be useful to handle any errors in the loaderror method handler on the js side and make decisions about further navigation.

### My problem appears when beforeload was added and after several get requests followed by a post request in inappbrowser.

The problem was solved by changing the following code:
```
- (void)webView:(WKWebView*)theWebView didFailProvisionalNavigation:(null_unspecified WKNavigation *)navigation withError:(nonnull NSError *)error
{
if ([error.domain isEqualToString:@"WebKitErrorDomain"] && error.code == 102)
return;
else
[self webView:theWebView failedNavigation:@"didFailProvisionalNavigation" withError:error];
}
```

Start at the iOS WKWebView delegate method didFailProvisionalNavigation and trace how navigation failures become the JavaScript loaderror event. Define the desired navigation-decision policy for WebKitErrorDomain code 102 and other load errors, including what completion should look like; the issue does not name a test or file beyond this entry point.

Written by the indexing model from the issue text.