--- a/xpcom/idl-parser/xpidl/header.py
+++ b/xpcom/idl-parser/xpidl/header.py
@@ -61,22 +61,20 @@ def attributeParamlist(a, getter):
                    attributeParamName(a))]
     if a.implicit_jscontext:
         l.insert(0, "JSContext* cx")
 
     return ", ".join(l)
 
 
 def attributeAsNative(a, getter, declType = 'NS_IMETHOD'):
-        deprecated = a.deprecated and "NS_DEPRECATED " or ""
-        params = {'deprecated': deprecated,
-                  'returntype': attributeReturnType(a, declType),
+        params = {'returntype': attributeReturnType(a, declType),
                   'binaryname': attributeNativeName(a, getter),
                   'paramlist': attributeParamlist(a, getter)}
-        return "%(deprecated)s%(returntype)s %(binaryname)s(%(paramlist)s)" % params
+        return "%(returntype)s %(binaryname)s(%(paramlist)s)" % params
 
 
 def methodNativeName(m):
     return m.binaryname is not None and m.binaryname or firstCap(m.name)
 
 
 def methodReturnType(m, macro):
     """macro should be NS_IMETHOD or NS_IMETHODIMP"""
@@ -388,18 +386,16 @@ def write_interface(iface, fd):
     foundcdata = False
     for m in iface.members:
         if isinstance(m, xpidl.CDATA):
             foundcdata = True
 
     if not foundcdata:
         fd.write("NS_NO_VTABLE ")
 
-    if iface.attributes.deprecated:
-        fd.write("MOZ_DEPRECATED ")
     fd.write(iface.name)
     if iface.base:
         fd.write(" : public %s" % iface.base)
     fd.write(iface_prolog % names)
 
     for key, group in itertools.groupby(iface.members, key=type):
         if key == xpidl.ConstMember:
             write_const_decls(group)  # iterator of all the consts

--- a/xpcom/idl-parser/xpidl/runtests.py
+++ b/xpcom/idl-parser/xpidl/runtests.py
@@ -28,25 +28,24 @@ class TestParser(unittest.TestCase):
 
     def testInterface(self):
         i = self.p.parse("[uuid(abc)] interface foo {};", filename='f')
         self.assertTrue(isinstance(i, xpidl.IDL))
         self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
         self.assertEqual("foo", i.productions[0].name)
 
     def testAttributes(self):
-        i = self.p.parse("[scriptable, builtinclass, function, deprecated, uuid(abc)] interface foo {};", filename='f')
+        i = self.p.parse("[scriptable, builtinclass, function, uuid(abc)] interface foo {};", filename='f')
         self.assertTrue(isinstance(i, xpidl.IDL))
         self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
         iface = i.productions[0]
         self.assertEqual("foo", iface.name)
         self.assertTrue(iface.attributes.scriptable)
         self.assertTrue(iface.attributes.builtinclass)
         self.assertTrue(iface.attributes.function)
-        self.assertTrue(iface.attributes.deprecated)
 
         i = self.p.parse("[noscript, uuid(abc)] interface foo {};", filename='f')
         self.assertTrue(isinstance(i, xpidl.IDL))
         self.assertTrue(isinstance(i.productions[0], xpidl.Interface))
         iface = i.productions[0]
         self.assertEqual("foo", iface.name)
         self.assertTrue(iface.attributes.noscript)
 

--- a/xpcom/idl-parser/xpidl/xpidl.py
+++ b/xpcom/idl-parser/xpidl/xpidl.py
@@ -597,17 +597,16 @@ class Interface(object):
         return total
 
 
 class InterfaceAttributes(object):
     uuid = None
     scriptable = False
     builtinclass = False
     function = False
-    deprecated = False
     noscript = False
     main_process_scriptable_only = False
 
     def setuuid(self, value):
         self.uuid = value.lower()
 
     def setscriptable(self):
         self.scriptable = True
@@ -616,29 +615,25 @@ class InterfaceAttributes(object):
         self.function = True
 
     def setnoscript(self):
         self.noscript = True
 
     def setbuiltinclass(self):
         self.builtinclass = True
 
-    def setdeprecated(self):
-        self.deprecated = True
-
     def setmain_process_scriptable_only(self):
         self.main_process_scriptable_only = True
 
     actions = {
         'uuid':       (True, setuuid),
         'scriptable': (False, setscriptable),
         'builtinclass': (False, setbuiltinclass),
         'function':   (False, setfunction),
         'noscript':   (False, setnoscript),
-        'deprecated': (False, setdeprecated),
         'object':     (False, lambda self: True),
         'main_process_scriptable_only': (False, setmain_process_scriptable_only),
         }
 
     def __init__(self, attlist, location):
         def badattribute(self):
             raise IDLError("Unexpected interface attribute '%s'" % name, location)
 
@@ -711,17 +706,16 @@ class Attribute(object):
     noscript = False
     readonly = False
     implicit_jscontext = False
     nostdcall = False
     must_use = False
     binaryname = None
     null = None
     undefined = None
-    deprecated = False
     infallible = False
 
     def __init__(self, type, name, attlist, readonly, location, doccomments):
         self.type = type
         self.name = name
         self.attlist = attlist
         self.readonly = readonly
         self.location = location
@@ -759,18 +753,16 @@ class Attribute(object):
             else:
                 if value is not None:
                     raise IDLError("Unexpected attribute value", aloc)
 
                 if name == 'noscript':
                     self.noscript = True
                 elif name == 'implicit_jscontext':
                     self.implicit_jscontext = True
-                elif name == 'deprecated':
-                    self.deprecated = True
                 elif name == 'nostdcall':
                     self.nostdcall = True
                 elif name == 'must_use':
                     self.must_use = True
                 elif name == 'infallible':
                     self.infallible = True
                 else:
                     raise IDLError("Unexpected attribute '%s'" % name, aloc)
@@ -817,17 +809,16 @@ class Method(object):
     kind = 'method'
     noscript = False
     notxpcom = False
     binaryname = None
     implicit_jscontext = False
     nostdcall = False
     must_use = False
     optional_argc = False
-    deprecated = False
 
     def __init__(self, type, name, attlist, paramlist, location, doccomments, raises):
         self.type = type
         self.name = name
         self.attlist = attlist
         self.params = paramlist
         self.location = location
         self.doccomments = doccomments
@@ -848,18 +839,16 @@ class Method(object):
             if name == 'noscript':
                 self.noscript = True
             elif name == 'notxpcom':
                 self.notxpcom = True
             elif name == 'implicit_jscontext':
                 self.implicit_jscontext = True
             elif name == 'optional_argc':
                 self.optional_argc = True
-            elif name == 'deprecated':
-                self.deprecated = True
             elif name == 'nostdcall':
                 self.nostdcall = True
             elif name == 'must_use':
                 self.must_use = True
             else:
                 raise IDLError("Unexpected attribute '%s'" % name, aloc)
 
         self.namemap = NameMap()