Add two way data binding.

sky/tests/framework/templates-expected.txt

Index: sky/tests/framework/templates-expected.txt
diff --git a/sky/tests/framework/templates-expected.txt b/sky/tests/framework/templates-expected.txt
index 587ea4eadca633ccc6441225ac52f629c206cdfd..b59402a73785cd2473a4d342ccdef3018255aba5 100644
--- a/sky/tests/framework/templates-expected.txt
+++ b/sky/tests/framework/templates-expected.txt
@@ -1,4 +1,4 @@
-Running 12 tests
+Running 13 tests
 ok 1 SkyElement should stamp when the element is inserted
 ok 2 SkyElement should update isAttached when inserting
 ok 3 SkyElement should handle parser created elements with attributes
@@ -8,9 +8,10 @@ ok 6 SkyElement should convert boolean reflected attributes
 ok 7 SkyElement should convert string reflected attributes
 ok 8 SkyElement should convert number reflected attributes
 ok 9 SkyElement should connect data binding
-ok 10 SkyElement should connect template event handlers
-ok 11 SkyElement should connect host event handlers
-ok 12 SkyElement should call shadowRootReady after creating the template instance
-12 tests
-12 pass
+ok 10 SkyElement should two way bind attributes
+ok 11 SkyElement should connect template event handlers
+ok 12 SkyElement should connect host event handlers
+ok 13 SkyElement should call shadowRootReady after creating the template instance
+13 tests
+13 pass
 0 fail