Fixing cleanup of dart:html annotation generation.

tools/dom/scripts/systemnative.py

Index: tools/dom/scripts/systemnative.py
diff --git a/tools/dom/scripts/systemnative.py b/tools/dom/scripts/systemnative.py
index 891b2875642324fb2af1d3969e88056d04f387c9..4ef1c98b0b2b1778f8a30f7c900dde1d1c496146 100644
--- a/tools/dom/scripts/systemnative.py
+++ b/tools/dom/scripts/systemnative.py
@@ -749,18 +749,15 @@ class DartiumBackend(HtmlDartGenerator):
 
   def _GenerateNativeBinding(self, idl_name, argument_count, dart_declaration,
       native_suffix, is_custom):
-    annotations = FindCommonAnnotations(self._interface.id, idl_name)
-    if annotations:
-      annotation_str = '\n  ' + '\n  '.join(annotations)
-    else:
-      annotation_str = ''
+    annotations = FormatAnnotations(
+        FindCommonAnnotations(self._interface.id, idl_name), '  ')
 
     native_binding = '%s_%s_%s' % (self._interface.id, idl_name, native_suffix)
     self._members_emitter.Emit(
-        '$ANNOTATIONS'
-        '\n  $DART_DECLARATION native "$NATIVE_BINDING";\n',
+        '\n'
+        '  $ANNOTATIONS$DART_DECLARATION native "$NATIVE_BINDING";\n',
         DOMINTERFACE=self._interface.id,
-        ANNOTATIONS=annotation_str,
+        ANNOTATIONS=annotations,
         DART_DECLARATION=dart_declaration,
         NATIVE_BINDING=native_binding)