Element createElement(
String tagName,
[String typeExtension]
)

Not documented.

Source

@DomName('Document.createElement')
Element createElement(String tagName, [String typeExtension]) {
  if (typeExtension != null) {
    return _createElement(tagName, typeExtension);
  } else {
    // Fast-path for Dartium when typeExtension is not needed.
    return _Utils.createElement(this, tagName);
  }
}