Edit transactions should store their editor instance with strong reference and they should be released at destroying the editor.
MozReview-Commit-ID: D67KU8WFxyo
Other transaction classes use EditorBase directly, but these transaction classes use nsIEditor. To remove nsIDOMDocument XPCOM interface usage, I would like to use EditorBase directly.
MozReview-Commit-ID: 3alRd9Zj5aZ
This patch also moves ImplCycleCollectionTraverse() and ImplCycleCollectionUnlink() to mozilla namespace for avoiding bustage due to confusion caused by "using namespace" in other unified cpp files.
MozReview-Commit-ID: GekPlZnqLs9