Updating .NET to not propagate non-W3C compliant capability names

Fixes issue #5646.

Author: jimevans

dotnet/src/webdriver/DriverOptions.cs

@@ -333,6 +333,11 @@ protected DesiredCapabilities GenerateDesiredCapabilities(bool isSpecificationCo
             if (this.Proxy != null)
             {
                 Dictionary<string, object> proxyCapability = this.Proxy.ToCapability();
+                if (!isSpecificationCompliant)
+                {
+                    proxyCapability = this.Proxy.ToLegacyCapability();
+                }
+
                 if (proxyCapability != null)
                 {
                     capabilities.SetCapability(CapabilityType.Proxy, proxyCapability);

dotnet/src/webdriver/Remote/CapabilityType.cs

@@ -16,6 +16,8 @@
 // limitations under the License.
 // </copyright>
 
+using System.Collections.Generic;
+
 namespace OpenQA.Selenium.Remote
 {
     /// <summary>
@@ -137,5 +139,25 @@ public static class CapabilityType
         /// Capability name used to indicate whether the driver supports web storage.
         /// </summary>
         public static readonly string SupportsWebStorage = "webStorageEnabled";
+
+        private static readonly List<string> KnownSpecCompliantCapabilityNames = new List<string>() {
+            BrowserName,
+            BrowserVersion,
+            PlatformName,
+            AcceptInsecureCertificates,
+            PageLoadStrategy,
+            Proxy,
+            UnhandledPromptBehavior
+        };
+
+        public static bool IsSpecCompliantCapabilityName(string capabilityName)
+        {
+            if (KnownSpecCompliantCapabilityNames.Contains(capabilityName) || capabilityName.Contains(":"))
+            {
+                return true;
+            }
+
+            return false;
+        }
     }
 }

dotnet/src/webdriver/Remote/RemoteWebDriver.cs

@@ -1158,7 +1158,7 @@ protected virtual Dictionary<string, object> GetCapabilitiesDictionary(ICapabili
             DesiredCapabilities capabilitiesObject = capabilitiesToConvert as DesiredCapabilities;
             foreach (KeyValuePair<string, object> entry in capabilitiesObject.CapabilitiesDictionary)
             {
-                if (entry.Key != CapabilityType.Version && entry.Key != CapabilityType.Platform)
+                if (CapabilityType.IsSpecCompliantCapabilityName(entry.Key))
                 {
                     capabilitiesDictionary.Add(entry.Key, entry.Value);
                 }