Fix bug 25303

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25303
* Algorithm oops ("context" instead of "parent")
* Grammatical correctness (":" instead of ".")
* Clarified "in order" ("tree order" or "order listed")
* [NewObject] WebIDL annotations
* No more needless "terminate this algorithm" statements
* Quoted and cross-linked exception names
* Improved example syntax for createContextualFragment

Author: travisleithead