[webcomponents] "component tree" is just "node tree" (#384)

It seems that the concept of [a component tree](https://w3c.github.io/webcomponents/spec/shadow/#dfn-component-tree) is redundant with [node tree](https://dom.spec.whatwg.org/#concept-node-tree).

Also I don't like the term [A primary component tree](https://w3c.github.io/webcomponents/spec/shadow/#dfn-primary-component-tree).  "component" seems like an arbitrary prefix that doesn't add any value;  It makes me think of a Web component, and that's a bad thing.  I think "primary tree" would be a better name.

Also, why is `DocumentFragment` left out in this concept?  All shadow root should be document fragments, right?

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/webcomponents/issues/384