Object.preventExtensions() should throw a TypeError if [[PreventExtensions]] returns false: - https://tc39.github.io/ecma262/#sec-object.preventextensions We currently do not throw.
Created attachment 287845 [details] Patch
Comment on attachment 287845 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=287845&action=review The code here doesn’t make sense to me. > Source/WebCore/bindings/js/JSDOMWindowCustom.cpp:349 > + throwTypeError(exec, scope, ASCIILiteral("Cannot prevent extensions on this object")); Should the message be more specific than "this object"?
Comment on attachment 287845 [details] Patch Clearing flags on attachment: 287845 Committed r205404: <http://trac.webkit.org/changeset/205404>
All reviewed patches have been landed. Closing bug.