Use Blink IDL parser for dart libraries.

tools/dom/scripts/systemhtml.py

Index: tools/dom/scripts/systemhtml.py
diff --git a/tools/dom/scripts/systemhtml.py b/tools/dom/scripts/systemhtml.py
index c5fb8a0a630a01f92b950c6a34d376b884dbc421..79e4b73796c76463f11197872d73eeebe68cee78 100644
--- a/tools/dom/scripts/systemhtml.py
+++ b/tools/dom/scripts/systemhtml.py
@@ -653,7 +653,7 @@ class Dart2JSBackend(HtmlDartGenerator):
   interface.
   """
 
-  def __init__(self, interface, options):
+  def __init__(self, interface, options, logging_level=logging.WARNING):
     super(Dart2JSBackend, self).__init__(interface, options, False)
 
     self._database = options.database
@@ -665,6 +665,8 @@ class Dart2JSBackend(HtmlDartGenerator):
     self._current_secondary_parent = None
     self._library_name = self._renamer.GetLibraryName(self._interface)
 
+    _logger.setLevel(logging_level)
+
   def ImplementsMergedMembers(self):
     return True