https://drafts.fxtf.org/geometry/#cloning

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When a user agent is asked to clone an DOMPointReadOnly, DOMPoint, DOMRectReadOnly, DOMRect, DOMQuad, DOMMatrixReadOnly or DOMMatrix object old, it must run the following steps, which return a new object of same type. These steps must be run atomically.

Create a new object new of the same type as old. Copy all member variable values from old to new.
Return new. It is the clone.
The above algorithm follows the “safe passing of structured data” [HTML5] definitions.
]]

Need to update this section in terms of https://html.spec.whatwg.org/multipage/infrastructure.html#safe-passing-of-structured-data