bind-gen: Support stringifier of IDL interface

Bug: 839389
Change-Id: I382b2f7eef3897248263a7c7dda8849f58ca1536
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2035630Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738436}

third_party/blink/renderer/bindings/scripts/bind_gen/codegen_context.py

@@ -57,6 +57,9 @@ class CodeGenContext(object):
             "operation": None,
             "operation_group": None,
 
+            # Special member-ish definition
+            "stringifier": None,
+
             # The names of the class being generated and its base class.
             "base_class_name": None,
             "class_name": None,
@@ -226,6 +229,9 @@ class CodeGenContext(object):
 
     @property
     def property_(self):
+        if self.stringifier:
+            return _StringifierProperty(self.stringifier)
+
         return (self.attribute or self.constant or self.constructor_group
                 or self.dict_member or self.exposed_construct
                 or self.operation_group)
@@ -244,3 +250,47 @@ class CodeGenContext(object):
 
 
 CodeGenContext.init()
+
+
+class _PropertyBase(object):
+    def __init__(self, identifier, extended_attributes, owner, debug_info):
+        assert isinstance(identifier, web_idl.Identifier)
+        assert identifier
+        assert isinstance(extended_attributes, web_idl.ExtendedAttributes)
+        assert isinstance(debug_info, web_idl.DebugInfo)
+
+        self._identifier = identifier
+        self._extended_attributes = extended_attributes
+        self._owner = owner
+        self._debug_info = debug_info
+
+    @property
+    def identifier(self):
+        return self._identifier
+
+    @property
+    def extended_attributes(self):
+        return self._extended_attributes
+
+    @property
+    def owner(self):
+        return self._owner
+
+    @property
+    def debug_info(self):
+        return self._debug_info
+
+
+class _StringifierProperty(_PropertyBase):
+    def __init__(self, stringifier):
+        if stringifier.attribute:
+            extended_attributes = stringifier.attribute.extended_attributes
+        else:
+            extended_attributes = stringifier.operation.extended_attributes
+
+        _PropertyBase.__init__(
+            self,
+            identifier=web_idl.Identifier("toString"),
+            extended_attributes=extended_attributes,
+            owner=stringifier.owner,
+            debug_info=stringifier.debug_info)

third_party/blink/renderer/bindings/scripts/web_idl/__init__.py

@@ -35,6 +35,8 @@ from .attribute import Attribute
 from .callback_function import CallbackFunction
 from .callback_interface import CallbackInterface
 from .composition_parts import Component
+from .composition_parts import DebugInfo
+from .composition_parts import Identifier
 from .constant import Constant
 from .constructor import Constructor
 from .constructor import ConstructorGroup
@@ -44,10 +46,17 @@ from .dictionary import Dictionary
 from .dictionary import DictionaryMember
 from .enumeration import Enumeration
 from .exposure import Exposure
+from .extended_attribute import ExtendedAttribute
+from .extended_attribute import ExtendedAttributes
 from .function_like import FunctionLike
 from .function_like import OverloadGroup
 from .idl_type import IdlType
 from .interface import Interface
+from .interface import Iterable
+from .interface import Maplike
+from .interface import PropertyAccessors
+from .interface import Setlike
+from .interface import Stringifier
 from .literal_constant import LiteralConstant
 from .namespace import Namespace
 from .operation import Operation