Support overloaded constructors.

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 8767e18e6a7948bebe1d19b0dd5ae4f717e470b5..1b0063a021da6d04ba96bf7ae71595381fb232da 100644
--- a/tools/dom/scripts/systemhtml.py
+++ b/tools/dom/scripts/systemhtml.py
@@ -522,56 +522,33 @@ class Dart2JSBackend(HtmlDartGenerator):
   def GetSupportCheck(self):
     return js_support_checks.get(self._interface.doc_js_name)
 
-  def EmitStaticFactory(self, constructor_info):
-    WITH_CUSTOM_STATIC_FACTORY = [
+  def GenerateCustomFactory(self, constructor_info):
+    # Custom factory will be taken from the template.
+    return self._interface.doc_js_name in [
         'AudioContext',
         'Blob',
         'MutationObserver',
         'SpeechRecognition',
     ]
 
-    if self._interface.doc_js_name in WITH_CUSTOM_STATIC_FACTORY:
-      return
-
-    has_optional = any(param_info.is_optional
-        for param_info in constructor_info.param_infos)
-
-    def FormatJS(index):
-      arguments = constructor_info.ParametersAsArgumentList(index)
-      if arguments:
-        arguments = ', ' + arguments
-      return "JS('%s', 'new %s(%s)'%s)" % (
-          self._interface_type_info.interface_name(),
-          constructor_info.name or self._interface.doc_js_name,
-          ','.join(['#'] * index),
-          arguments)
+  def IsConstructorArgumentOptional(self, argument):
+    return 'Optional' in argument.ext_attrs
 
-    if not has_optional:
-      self._members_emitter.Emit(
-          "  static $INTERFACE_NAME _create($PARAMETERS_DECLARATION) => $JS;\n",
-          INTERFACE_NAME=self._interface_type_info.interface_name(),
-          PARAMETERS_DECLARATION=constructor_info.ParametersDeclaration(
-              self._DartType),
-          JS=FormatJS(len(constructor_info.param_infos)))
-    else:
-      dispatcher_emitter = self._members_emitter.Emit(
-          "  static $INTERFACE_NAME _create($PARAMETERS_DECLARATION) {\n"
-          "$!DISPATCHER"
-          "    return $JS;\n"
-          "  }\n",
-          INTERFACE_NAME=self._interface_type_info.interface_name(),
-          PARAMETERS_DECLARATION=constructor_info.ParametersDeclaration(
-              self._DartType),
-          JS=FormatJS(len(constructor_info.param_infos)))
-
-      for index, param_info in enumerate(constructor_info.param_infos):
-        if param_info.is_optional:
-          dispatcher_emitter.Emit(
-            "    if (!?$OPT_PARAM_NAME) {\n"
-            "      return $JS;\n"
-            "    }\n",
-            OPT_PARAM_NAME=constructor_info.param_infos[index].name,
-            JS=FormatJS(index))
+  def EmitStaticFactoryOverload(self, constructor_info, name, arguments):
+    index = len(arguments)
+    arguments = constructor_info.ParametersAsArgumentList(index)
+    if arguments:
+      arguments = ', ' + arguments
+    self._members_emitter.Emit(
+        "  static $INTERFACE_NAME $NAME($PARAMETERS) => "
+          "JS('$INTERFACE_NAME', 'new $CTOR_NAME($PLACEHOLDERS)'$ARGUMENTS);\n",
+        INTERFACE_NAME=self._interface_type_info.interface_name(),
+        NAME=name,
+        # TODO(antonm): add types to parameters.
+        PARAMETERS=constructor_info.ParametersAsArgumentList(index),
+        CTOR_NAME=constructor_info.name or self._interface.doc_js_name,
+        PLACEHOLDERS=','.join(['#'] * index),
+        ARGUMENTS=arguments)
 
   def SecondaryContext(self, interface):
     if interface is not self._current_secondary_parent: