[dotnet] Allow setting of PageDimensions and PageMargins in PrintOptions directly

dotnet/src/webdriver/PrintOptions.cs

@@ -101,19 +101,21 @@ public bool ShrinkToFit
         }
 
         /// <summary>
-        /// Gets the dimensions for each page in the printed document.
+        /// Gets or sets the dimensions for each page in the printed document.
         /// </summary>
         public PageSize PageDimensions
         {
             get { return pageSize; }
+            set { pageSize = value; }
         }
 
         /// <summary>
-        /// Gets the margins for each page in the doucment.
+        /// Gets or sets the margins for each page in the doucment.
         /// </summary>
         public Margins PageMargins
         {
             get { return margins; }
+            set { margins = value; }
         }
 
         /// <summary>