[dotnet] Add dispose on constructor failure to ensure driver closes

dotnet/src/webdriver/WebDriver.cs

@@ -54,7 +54,18 @@ public class WebDriver : IWebDriver, ISearchContext, IJavaScriptExecutor, IFinds
         protected WebDriver(ICommandExecutor executor, ICapabilities capabilities)
         {
             this.executor = executor;
-            this.StartSession(capabilities);
+
+            try
+            {
+                this.StartSession(capabilities);
+            }
+            catch (Exception)
+            {
+                // Failed to start driver session, disposing of driver
+                this.DriverDispose();
+                throw;
+            }
+
             this.elementFactory = new WebElementFactory(this);
             this.network = new NetworkManager(this);
             this.registeredCommands.AddRange(DriverCommand.KnownCommands);
@@ -674,6 +685,15 @@ protected bool RegisterInternalDriverCommand(string commandName, CommandInfo com
         /// </summary>
         /// <param name="disposing">if its in the process of disposing</param>
         protected virtual void Dispose(bool disposing)
+        {
+            this.DriverDispose();
+            this.executor.Dispose();
+        }
+
+        /// <summary>
+        /// Send Quit command to stop driver
+        /// </summary>
+        protected virtual void DriverDispose()
         {
             try
             {
@@ -692,8 +712,6 @@ protected virtual void Dispose(bool disposing)
             {
                 this.sessionId = null;
             }
-
-            this.executor.Dispose();
         }
 
         private static void UnpackAndThrowOnError(Response errorResponse, string commandToExecute)