Some events not set to null in Dispose

[bddckr]

• What version of the product are you using?
  CefSharp.OffScreen Version 63.0.1 (Should be the same on 63.0.2, though, because I checked the cefsharp/63 branch at 190c3af)

• What architecture x86 or x64?
  x64

• On what operating system?
  Win10

• Are you using WinForms, WPF or OffScreen?
  OffScreen

• What steps will reproduce the problem?
  I have a weird scenario in which it's really hard for me to unsubscribe from events on a browser instance before it's disposed by another component. Since there is no Disposing event on the CefSharp components I'm relying on the components turning their events to null in their dispose.
  I'm currently in the process to actually remedy this issue on my end by not relying on implementation details of CefSharp 😉

• What is the expected output? What do you see instead?
  I'm expecting all events to be set to null to stop referencing any event listener. There are some events that aren't set to null, so I have some event listener objects stay around a bit.

• Please provide any additional information below.
  I only had a look at the CefSharp.OffScreen.ChromiumWebBrowser component and its JavascriptObjectRepository. Here's what I found:
  

  CefSharp/CefSharp.OffScreen/ChromiumWebBrowser.cs

  Lines 360 to 370 in 8d642df

  	protected virtual void Dispose(bool disposing)
  	{
  	// Don't reference event listeners any longer:
  	LoadError = null;
  	FrameLoadStart = null;
  	FrameLoadEnd = null;
  	ConsoleMessage = null;
  	BrowserInitialized = null;
  	StatusMessage = null;
  	LoadingStateChanged = null;
  	AddressChanged = null;

  
  Missing: TitleChanged, Paint/OnPaint+NewScreenshot (depending on branch used: master vs. cefsharp/63)
  

  CefSharp/CefSharp/Internals/JavascriptObjectRepository.cs

  Lines 54 to 57 in 8d642df

  	public void Dispose()
  	{
  	ResolveObject = null;
  	}

  
  Missing: ObjectBoundInJavascript

• Does this problem also occur in the CEF Sample Application from http://opensource.spotify.com/cefbuilds/index.html?
  Doesn't apply.

[amaitland]

Sounds reasonable. Pull requests welcome.

You can add your own disposed event to work around the problem in the short term.

[bddckr]

That's exactly what I'm doing actually! 😄

I'll do a PR but that will have to wait ~2-4 weeks. Since this isn't a big issue (event listeners should be unsubscribed properly instead) I hope that's OK!

[amaitland]

WinForms and WPF versions should be reviewed as well.