Parsoid/Todo:PHP parser integration

Extension expansion
Most extensions don't depend on order and frame state, so can be expanded in parallel and out-of-order.

The following extensions probably depend on the frame state :
 * Arrays (frame->expand, shared state so order-dependent)
 * CreatePage (frame->expand)
 * Description2 (frame->expand)
 * ExtTab / ET_ParserFunction (frame->expand)
 * GeoData (frame->expand)
 * HashTables (frame->expand, frame->getArguments, order-dependent)
 * LabeledSectionTransclusion (frame->expand)
 * Loops (frame->expand, frame->getArgument, order/nesting-dependent)
 * Scribunto (frame->getArguments)