It's been passed in for a while, but nothing ever used it. As we know
some browsers don't like it when we create elements in the wrong
document, and this ensures we always use the correct document for
createElement().
Change-Id: Ia3d2fabe0516956105ad2b5625ed2f76c015c26e
Rather than meta-things being special kinds of nodes, they are now a
separate class of things (MetaItems) along with Nodes and Annotations.
* Created a generic ve.dm.MetaItem that meta items inherit from.
There will be actual instances of this class as well in the upcoming
meta group code.
* Renamed MetaNode to AlienMetaItem, MWMetaNode to MWMetaItem,
'metaBlock'/'metaInline' to 'alienMeta'
* Created a MetaItemFactory, handle meta items in the ModelRegistry
* Kill ve.dm.Node.static.isMeta, now obsolete
ve.dm.Converter:
* Pass in the MetaItemFactory
* Look up data element types in the ModelRegistry rather than the
NodeFactory, because they can be either nodes or meta items
* Document createDataElement() and make explicit that modelClass can be
either a node or a meta item
* Handle meta items in getDataFromDom()
* In getDomFromData(), check the MetaItemFactory as well as the NodeFactory
Change-Id: I893709c6f3aa00f85c1b905b70f9f4e597bdeada
