Switch to equalIgnoringASCIICase throughout modules/accessibility

BUG=627682

Review-Url: https://codereview.chromium.org/2793913007
Cr-Commit-Position: refs/heads/master@{#461858}
String AXNodeObject::valueDescription() const {
  if (!supportsRangeValue())
    return String();

  return getAOMPropertyOrARIAAttribute(AOMStringProperty::kValueText)
      .getString();
}

String AXNodeObject::valueDescription() const {
  if (!supportsRangeValue())
    return String();

  return getAOMPropertyOrARIAAttribute(AOMStringProperty::kValueText)
      .getString();
}
