fix #136, support watch exprs and two way bindings for component fields

test/data/expected/component_field_2way_test.html.txt

Index: test/data/expected/component_field_2way_test.html.txt
diff --git a/test/data/expected/component_field_2way_test.html.txt b/test/data/expected/component_field_2way_test.html.txt
new file mode 100644
index 0000000000000000000000000000000000000000..521c58634a8e33f67d49bfac48e848d69637cac1
--- /dev/null
+++ b/test/data/expected/component_field_2way_test.html.txt
@@ -0,0 +1,20 @@
+Blocked access to external URL http://dart.googlecode.com/svn/branches/bleeding_edge/dart/client/dart.js
+Blocked access to external URL http://dart.googlecode.com/svn/branches/bleeding_edge/dart/client/dart.js
+Content-Type: text/plain
+layer at (0,0) size 800x600
+  RenderView at (0,0) size 800x600
+layer at (0,0) size 800x88
+  RenderBlock {HTML} at (0,0) size 800x88
+    RenderBody {BODY} at (8,16) size 784x56
+      RenderBlock {P} at (0,0) size 784x20
+        RenderText {#text} at (0,0) size 426x19
+          text run at (0,0) width 426: "The message changes from \"hello world\" to something more interesting."
+      RenderBlock {X-GREETER} at (0,36) size 784x0
+      RenderBlock {P} at (0,36) size 784x20
+        RenderText {#text} at (0,0) size 56x19
+          text run at (0,0) width 56: "Yo dawg"
+        RenderText {#text} at (56,0) size 4x19
+          text run at (56,0) width 4: " "
+        RenderText {#text} at (60,0) size 311x19
+          text run at (60,0) width 311: "I heard you like world so we put world in yo world."
+#EOF