1. DomName('SVGTextContentElement.getSubStringLength')
  2. DocsEditable()
num getSubStringLength(int offset, int length)

Source 

@DomName('SVGTextContentElement.getSubStringLength')
@DocsEditable()
num getSubStringLength(int offset, int length) => _blink.BlinkSVGTextContentElement.instance.getSubStringLength_Callback_2_(unwrap_jso(this), offset, length);