### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

12.0.1

### What operating system are you using?

macOS

### Operating System Version

11.2

### What arch are you using?

x64

### Last Known Working Electron version

11.x

### Expected Behavior

The app should not crash, and the new-window event should be fired

### Actual Behavior

The app crashes 

### Testcase Gist URL

https://gist.github.com/ae7fdfd99a5d755a5ae4323c46a4e833


shell/browser/web_view_guest_delegate.cc
#include "shell/browser/web_view_guest_delegate.h"
#include <memory>
#include "content/browser/web_contents/web_contents_impl.h"  
#include "content/public/browser/navigation_handle.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/render_view_host.h"
#include "content/public/browser/render_widget_host.h"
#include "content/public/browser/render_widget_host_view.h"
#include "shell/browser/api/electron_api_web_contents.h"
#include "third_party/blink/public/common/page/page_zoom.h"
namespace electron {
WebViewGuestDelegate::WebViewGuestDelegate(content::WebContents* embedder,
                                           api::WebContents* api_web_contents)
    : embedder_web_contents_(embedder), api_web_contents_(api_web_contents) {}
WebViewGuestDelegate::~WebViewGuestDelegate() {
  ResetZoomController();
}
void WebViewGuestDelegate::AttachToIframe(