headingLevel property
Indicates the heading level in the document structure.
This is only used for web semantics, and is ignored on other platforms.
Implementation
int get headingLevel => _headingLevel;Implementation
set headingLevel(int value) {
  assert(value >= 0 && value <= 6);
  if (value == headingLevel) {
    return;
  }
  _headingLevel = value;
  _hasBeenAnnotated = true;
}