PR c++/84449
	* tree.c (bot_manip): If build_cplus_new or break_out_target_exprs
	returns error_mark_node, return it immediately.
	(break_out_target_exprs): If cp_walk_tree with bot_manip returns
	error_mark_node, return error_mark_node.

	* g++.dg/cpp0x/constexpr-84449.C: New test.

From-SVN: r257839