Tests that source data is extracted correctly from stylesheets with @keyframes rules.
Running: testInit
Running: testDumpStyles
[expanded]
element.style { ()
background-color: white;
[expanded]
* { (<style>)
/-- overloaded --/ background-color: papayawhip;
[expanded]
div { (user agent stylesheet)
display: block;
unicode-bidi: isolate;