[mdv] implement Node.createBinding and Node.createBindings

pkg/observe/lib/src/change_record.dart

Index: pkg/observe/lib/src/change_record.dart
diff --git a/pkg/observe/lib/src/change_record.dart b/pkg/observe/lib/src/change_record.dart
index 652e89e071fbc6b7667ce9a740dc3c8c3bff3348..99e806ddb373b56d528f884d74be91dd7413badc 100644
--- a/pkg/observe/lib/src/change_record.dart
+++ b/pkg/observe/lib/src/change_record.dart
@@ -6,8 +6,9 @@ part of observe;
 
 /** Records a change to an [Observable]. */
 abstract class ChangeRecord {
+  // TODO(jmesserly): rename this--it's confusing. Perhaps "matches"?
   /** True if the change affected the given item, otherwise false. */
-  bool change(key);
+  bool changes(key);
 }
 
 /** A change record to a field of an observable object. */