Update from https://crrev.com/308996

sky/engine/bindings/scripts/blink_idl_parser.py

Index: sky/engine/bindings/scripts/blink_idl_parser.py
diff --git a/sky/engine/bindings/scripts/blink_idl_parser.py b/sky/engine/bindings/scripts/blink_idl_parser.py
index 1e226051b8a4c08370165b944573aa7f9b46d534..87b32198dcdd0862ee04206feb63a67574d5c174 100644
--- a/sky/engine/bindings/scripts/blink_idl_parser.py
+++ b/sky/engine/bindings/scripts/blink_idl_parser.py
@@ -254,7 +254,13 @@ class BlinkIDLParser(IDLParser):
         # ExceptionFields, and Attribute removed from this rule.
         p[0] = p[1]
 
-    # [b47.1]
+    # [b47.1] FIXME: rename to ExceptionAttribute
+    def p_Attribute(self, p):
+        """Attribute : ReadOnly ATTRIBUTE Type identifier ';'"""
+        p[0] = self.BuildNamed('Attribute', p, 4,
+                               ListFromConcat(p[1], p[3]))
+
+    # [b47.2]
     def p_ExceptionOperation(self, p):
         """ExceptionOperation : Type identifier '(' ')' ';'"""
         # Needed to handle one case in DOMException.idl:
@@ -275,6 +281,12 @@ class BlinkIDLParser(IDLParser):
             items = ListFromConcat(p[2], p[3])
             p[0] = self.BuildProduction('ExtAttributes', p, 1, items)
 
+    # Error handling for ExtendedAttributeList.
+    # We can't upstream this because we override ExtendedAttributeList.
+    def p_ExtendedAttributeListError(self, p):
+        """ExtendedAttributeList : '[' ExtendedAttribute ',' error"""
+        p[0] = self.BuildError(p, "ExtendedAttributeList")
+
     # [b50] Allow optional trailing comma
     # Blink-only, marked as WONTFIX in Web IDL spec:
     # https://www.w3.org/Bugs/Public/show_bug.cgi?id=22156