This tests that the main frame doesn't have access to a data: URL loaded in an iframe inside another data: URL loaded iframe.
PASS: Cross frame access to a data: URL 2 levels deep was denied.
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Frame: 'aFrame'
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Inner iframe.
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Frame: '<!--framePath //aFrame/<!--frame0-->-->'
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PASS: Cross frame access to a data: URL 2 levels deep was denied.
Inner-inner iframe.