Do not allocate empty collections for child nodes or attributes when
initializing new HTML Nodes or Elements. These are initialized the first
time they are accessed.
Analogously, the mutable data string of CharacterData is also allocated
with the empty string on first access.
The data property is longer exposed as a mutable string. Instead all
manipulations must be performed via the provided API in order to ensure
correct updates for the Document’s attached ranges.
See:
https://dom.spec.whatwg.org/#characterdata
iska