code: void setParent (Context2 parent)
      {
          this.parent = parent;
          parent.child = this;        // JJK: Doubly-linked
          declarations = null;
          prefixTable = parent.prefixTable;
          uriTable = parent.uriTable;
          elementNameTable = parent.elementNameTable;
          attributeNameTable = parent.attributeNameTable;
          defaultNS = parent.defaultNS;
          tablesDirty = false;
      }
docs: (Re)set the parent of this Namespace context.
  This is separate from the c'tor because it's re-applied
  when a Context2 is reused by push-after-pop.
  
  @param context The parent Namespace context object.