Opera 9.50 weekly
Opera が document.all を試験的に対応する版。
It's not standardised, but the Web has plenty of pages that don't use fully standardised code, and we have to work with them, or you won't be able to use them. A long time ago, Opera was forced to add support for document.all because of this.
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For what it's worth, we are not the first to do this. Two other popular browsers (Firefox and Safari) tried not supporting it, and found that broke too many pages, so they both now have cloaked support for it.
Friday Night Beer で酔っているので正確には思い出せないが、Opera 7 の時代には Quirks mode の時だけ document.all をサポートするようなことをしていたのではなかったか。（この項、いつもに増して好い加減。）
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