Adding exception handling in .NET WebDriverBackedSelenium

Against my better judgement making any changes here whatsoever.

Fixes issue #4248.

Author: jimevans

dotnet/src/core/SeleniumException.cs

@@ -39,5 +39,14 @@ public SeleniumException()
 		public SeleniumException(string message) : base(message)
 		{
 		}
+
+		/// <summary>
+		/// Creates an exception with the specified message and inner exception
+		/// </summary>
+		/// <param name="message">the message to add to the exception</param>
+        /// <param name="innerException">the inner exception wrapped by this exception</param>
+        public SeleniumException(string message, Exception innerException) : base(message, innerException)
+		{
+		}
 	}
 }

dotnet/src/webdriverbackedselenium/Internal/CommandTimer.cs

@@ -77,6 +77,14 @@ private void RunCommand()
             {
                 this.thrownException = e;
             }
+            catch (WebDriverException e)
+            {
+                this.thrownException = new SeleniumException("WebDriver exception thrown", e);
+            }
+            catch (InvalidOperationException e)
+            {
+                this.thrownException = new SeleniumException("WebDriver exception thrown", e);
+            }
         }
     }
 }