text/internal/gen: generalized Open (needed for w3c data).
text/internal/gen: generalized Open (needed for w3c data).

Change-Id: I6fe6e9983921a593eb706f829184b5f39b8246fe
Reviewed-on: https://go-review.googlesource.com/7671
Reviewed-by: Nigel Tao <58ae08b3356928ff9c67562b4719487d54fe8348@golang.org>

cmars/tools,cmars/tools,cmars/tools,cmars/tools,npchp110/text,golang/text