div id="target9" style="margin: var(--prop); margin-top: 10px"></div>
<div id="target10"style="expando: var(--prop);"></div>

<script type="text/javascript">
    "use strict";

    var testcases = [
        { element: "target1",   expectedCssText: "--var: var1;" },
        { element: "target2",   expectedCssText: "margin: var(--prop);" },
        { element: "target3",   expectedCssText: "background: var(--prop);" },
        { element: "target4",   expectedCssText: "margin: var(--prop) !important;" },
      