var expandoValue = "WebGL is awesome!"
function setTestExpandos(instance, extra) {
    instance.expando1 = expandoValue;
    instance.expando2 = { subvalue : expandoValue };
    instance.expando_extra = extra;
}
function verifyTestExpandos(instance, msg, extra) {
    assertMsg(instance.expando1 === expandoValue, msg + ": Expect basic expando to survive despite GC.");
    assertMsg(instance.expando2 && instance.expando2.subvalue === expandoValue, msg + ": Expect subobject expando to survive despite GC.");
  