document.accessibilityAttributeNames.has(AXLoadingProgress)='yes'
document.accessibilityAttributeValue(AXLoadingProgress)=1
not_applicable.accessibilityAttributeNames.has(AXLoadingProgress)='no'
// Test of AccessibilityAttributeValue for "not applicable" element is
// necessary because the value can be requested.
not_applicable.accessibilityAttributeValue(AXLoadingProgress)=1