Fix serialization of alias_for properties

LayoutTests/transitions/transitions-parsing.html

Index: LayoutTests/transitions/transitions-parsing.html
diff --git a/LayoutTests/transitions/transitions-parsing.html b/LayoutTests/transitions/transitions-parsing.html
index ddb6ebdd60b427b53bf5df570672d44a12327873..75e8134c6b625a814a8998a8ce3765e5cdc042b8 100644
--- a/LayoutTests/transitions/transitions-parsing.html
+++ b/LayoutTests/transitions/transitions-parsing.html
@@ -49,6 +49,10 @@ shouldBe("computedStyle.transitionProperty", "'all, all'");
 shouldBe("style.webkitTransitionProperty", "'all, all'");
 shouldBe("computedStyle.webkitTransitionProperty", "'all, all'");
 
+style.transitionProperty = "-webkit-transform-origin";
+shouldBe("style.transitionProperty", "'-webkit-transform-origin'");
+shouldBe("computedStyle.transitionProperty", "'-webkit-transform-origin'");
+
 style.transitionProperty = "background-position";
 shouldBe("style.transitionProperty", "'background-position'");
 shouldBe("computedStyle.transitionProperty", "'background-position'");