This makes the document picture-in-picture Document's mode (quirks mode vs no-quirks-mode) match the mode of the opener Document. Currently, the empty document is quirks mode by default, so this allows websites that rely on non-quirks mode to still function properly within a document picture-in-picture window.
Currently, the empty document is quirks mode by default, so this allows websites that rely on non-quirks mode to still function properly within a document picture-in-picture window.