LegacyBinding - Remove objects from cache if key already exists

Temp fix for #2301 Will be resolved properly in #2306

CefSharp.BrowserSubprocess.Core/CefAppUnmanagedWrapper.cpp

@@ -478,6 +478,16 @@ namespace CefSharp
 
                 for each (JavascriptObject^ obj in Enumerable::OfType<JavascriptObject^>(javascriptObjects))
                 {
+                    //Using LegacyBinding with multiple ChromiumWebBrowser instances that share the same
+                    //render process and using LegacyBinding will cause problems for the limited caching implementation
+                    //that exists at the moment, for now we'll remove an object if already exists, same behaviour
+                    //as the new binding method. 
+                    //TODO: This should be removed when https://github.com/cefsharp/CefSharp/issues/2306
+                    //Is complete as objects will be stored at the browser level
+                    if (_javascriptObjects->ContainsKey(obj->JavascriptName))
+                    {
+                        _javascriptObjects->Remove(obj->JavascriptName);
+                    }
                     _javascriptObjects->Add(obj->JavascriptName, obj);
                 }
             }