IDL compiler: Support unwrap of variadic argument types

IdlType.unwrap supports variadic={True,False} in addition to
nullable and typedef.

Bug: 839389
Change-Id: I2f2d2cb2a79e0c33f56ab9df4d322f778c756dee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1932137Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718551}

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

@@ -225,14 +225,15 @@ def bind_v8_set_return_value(code_node, cg_context):
     _1 = "V8SetReturnValue"
     _2 = ["${info}", "${return_value}"]
 
-    if cg_context.return_type.unwrap().is_void:
+    return_type = cg_context.return_type.unwrap(nullable=True, typedef=True)
+    if return_type.is_void:
         # Render a SymbolNode |return_value| discarding the content text, and
         # let a symbol definition be added.
         pattern = "<% str(return_value) %>"
     elif (cg_context.for_world == cg_context.MAIN_WORLD
-          and cg_context.return_type.unwrap().is_interface):
+          and return_type.is_interface):
         _1 = "V8SetReturnValueForMainWorld"
-    elif cg_context.return_type.unwrap().is_interface:
+    elif return_type.is_interface:
         _2.append("${creation_context_object}")
 
     text = _format(pattern, _1=_1, _2=", ".join(_2))

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

@@ -219,7 +219,7 @@ class IdlType(WithExtendedAttributes, WithDebugInfo):
         """
         callback(self)
 
-    def unwrap(self, nullable=None, typedef=None):
+    def unwrap(self, nullable=None, typedef=None, variadic=None):
         """
         Returns the body part of the actual type, i.e. returns the interesting
         part of this type.
@@ -237,6 +237,7 @@ class IdlType(WithExtendedAttributes, WithDebugInfo):
         switches = {
             'nullable': nullable,
             'typedef': typedef,
+            'variadic': variadic,
         }
 
         value_counts = {None: 0, False: 0, True: 0}
@@ -886,6 +887,11 @@ class VariadicType(_ArrayLikeType):
     def is_variadic(self):
         return True
 
+    def _unwrap(self, switches):
+        if switches['variadic']:
+            return self.element_type._unwrap(switches)
+        return self
+
 
 class RecordType(IdlType):
     """https://heycam.github.io/webidl/#idl-record"""