[dotnet] Add WebDriverWait constructor for specifying a sleep interval without a clock

dotnet/src/support/UI/PopupWindowFinder.cs

@@ -130,7 +130,7 @@ public string Invoke(Action popupMethod)
 
         ReadOnlyCollection<string> existingHandles = this.driver.WindowHandles;
         popupMethod();
-        WebDriverWait wait = new WebDriverWait(SystemClock.Instance, this.driver, this.timeout, this.sleepInterval);
+        var wait = new WebDriverWait(this.driver, this.timeout, this.sleepInterval);
         string popupHandle = wait.Until(driver =>
         {
             ReadOnlyCollection<string> newHandles = driver.WindowHandles;

dotnet/src/webdriver/Support/WebDriverWait.cs

@@ -58,5 +58,17 @@ public WebDriverWait(IClock clock, IWebDriver driver, TimeSpan timeout, TimeSpan
         this.IgnoreExceptionTypes(typeof(NotFoundException));
     }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="WebDriverWait"/> class.
+    /// </summary>
+    /// <param name="driver">The WebDriver instance used to wait.</param>
+    /// <param name="timeout">The timeout value indicating how long to wait for the condition.</param>
+    /// <param name="sleepInterval">A <see cref="TimeSpan"/> value indicating how often to check for the condition to be true.</param>
+    /// <exception cref="ArgumentNullException">If <paramref name="driver"/> is <see langword="null"/>.</exception>
+    public WebDriverWait(IWebDriver driver, TimeSpan timeout, TimeSpan sleepInterval)
+        : this(SystemClock.Instance, driver, timeout, DefaultSleepTimeout)
+    {
+    }
+
     private static TimeSpan DefaultSleepTimeout => TimeSpan.FromMilliseconds(500);
 }