Bindings generator should support Web IDL callback interfaces

Source/bindings/tests/idls/TestCallback.idl

Index: Source/bindings/tests/idls/TestCallback.idl
diff --git a/Source/bindings/tests/idls/TestCallback.idl b/Source/bindings/tests/idls/TestCallback.idl
index 8cc982be1f6f4d03aadc816422bfa093ff0fda58..ea6a5eb4012ac3a3e45db2287a9e38ebe40f83e5 100644
--- a/Source/bindings/tests/idls/TestCallback.idl
+++ b/Source/bindings/tests/idls/TestCallback.idl
@@ -26,11 +26,9 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-// This IDL file is for testing the bindings code generator with an interface
-// that has the "Callback" attribute and for tracking changes in its ouput.
-[
-    Callback
-] interface TestCallback {
+// This IDL file is for testing the bindings code generator with a callback
+// interface for tracking changes in its ouput.
+callback interface TestCallback {
   boolean callbackWithNoParam();
   boolean callbackWithClass1Param(Class1 class1Param);
   boolean callbackWithClass2Param(Class2 class2Param, DOMString strArg);