Support overloaded constructors.

tools/dom/scripts/idlnode.py

Index: tools/dom/scripts/idlnode.py
diff --git a/tools/dom/scripts/idlnode.py b/tools/dom/scripts/idlnode.py
index 7c488a5ef8ef2a419f1a5f5f17ee266f08744583..74429127409e695e9167afe7d6dd762b72b56fbb 100755
--- a/tools/dom/scripts/idlnode.py
+++ b/tools/dom/scripts/idlnode.py
@@ -216,6 +216,9 @@ class IDLDictNode(IDLNode):
   def get(self, key, default=None):
     return self.__map.get(key, default)
 
+  def setdefault(self, key, value=None):
+    return self.__map.setdefault(key, value)
+
   def items(self):
     return self.__map.items()
 
@@ -287,6 +290,18 @@ class IDLExtAttrs(IDLDictNode):
       name = self._find_first(ext_attr, 'Id')
       value = self._find_first(ext_attr, 'ExtAttrValue')
 
+      if name == 'Constructor':
+        # There might be multiple constructor attributes, collect them
+        # as a list.  Represent plain Constructor attribute
+        # (without any signature) as None.
+        assert value is None
+        func_value = None
+        ctor_args = self._find_first(ext_attr, 'ExtAttrArgList')
+        if ctor_args:
+          func_value = IDLExtAttrFunctionValue(None, ctor_args)
+        self.setdefault('Constructor', []).append(func_value)
+        continue
+
       func_value = self._find_first(value, 'ExtAttrFunctionValue')
       if func_value:
         # E.g. NamedConstructor=Audio(in [Optional] DOMString src)
@@ -295,12 +310,6 @@ class IDLExtAttrs(IDLDictNode):
             self._find_first(func_value, 'ExtAttrArgList'))
         continue
 
-      ctor_args = not value and self._find_first(ext_attr, 'ExtAttrArgList')
-      if ctor_args:
-        # E.g. Constructor(Element host)
-        self[name] = IDLExtAttrFunctionValue(None, ctor_args)
-        continue
-
       self[name] = value
 
   def _all_subnodes(self):