DevTools - Add ToBase64String not implemented overload to get builds passing.

Will need to be handled at a later time

Author: amaitland

CefSharp.Core/DevTools/DevToolsDomainBase.cs

@@ -138,5 +138,10 @@ protected string ToBase64String(byte[] bytes)
         {
             return Convert.ToBase64String(bytes);
         }
+
+        protected string ToBase64String(byte[][] bytes)
+        {
+            throw new NotImplementedException("Not currently supported.");
+        }
     }
 }