remove unneeded tags from metadata

stage1 release rlib sizes:
580890 liballoc-bb943c5a.rlib
1425558 liballoc_jemalloc-bb943c5a.rlib
10514 liballoc_system-bb943c5a.rlib
157192 libarena-bb943c5a.rlib
4316234 libcollections-bb943c5a.rlib
19580128 libcore-bb943c5a.rlib
199498 libflate-bb943c5a.rlib
249328 libfmt_macros-bb943c5a.rlib
560406 libgetopts-bb943c5a.rlib
233620 libgraphviz-bb943c5a.rlib
442964 liblibc-bb943c5a.rlib
190178 liblog-bb943c5a.rlib
778488 librand-bb943c5a.rlib
621972 librbml-bb943c5a.rlib
1415040 librustc_back-bb943c5a.rlib
38849082 librustc-bb943c5a.rlib
12862 librustc_bitflags-bb943c5a.rlib
2331690 librustc_borrowck-bb943c5a.rlib
616880 librustc_data_structures-bb943c5a.rlib
9386582 librustc_driver-bb943c5a.rlib
9600440 librustc_front-bb943c5a.rlib
1615058 librustc_lint-bb943c5a.rlib
79218480 librustc_llvm-bb943c5a.rlib
5020974 librustc_mir-bb943c5a.rlib
3535448 librustc_platform_intrinsics-bb943c5a.rlib
603640 librustc_privacy-bb943c5a.rlib
3163628 librustc_resolve-bb943c5a.rlib
14326646 librustc_trans-bb943c5a.rlib
12033174 librustc_typeck-bb943c5a.rlib
1838202 librustc_unicode-bb943c5a.rlib
15611582 librustdoc-bb943c5a.rlib
3056280 libserialize-bb943c5a.rlib
8954312 libstd-bb943c5a.rlib
30906736 libsyntax-bb943c5a.rlib
925480 libterm-bb943c5a.rlib
1377952 libtest-bb943c5a.rlib

1 files changed, 0 insertions, 12 deletions

diff --git a/src/librustc/metadata/decoder.rs b/src/librustc/metadata/decoder.rs
index 77863ee3c87..be2fe7ddf7c 100644
--- a/src/librustc/metadata/decoder.rs
+++ b/src/librustc/metadata/decoder.rs
@@ -979,18 +979,6 @@ pub fn get_associated_consts<'tcx>(intr: Rc<IdentInterner>,
     }).collect()
 }
 
-pub fn get_type_name_if_impl(cdata: Cmd,
-                             node_id: ast::NodeId) -> Option<ast::Name> {
-    let item = cdata.lookup_item(node_id);
-    if item_family(item) != Impl {
-        return None;
-    }
-
-    reader::tagged_docs(item, tag_item_impl_type_basename).nth(0).map(|doc| {
-        token::intern(doc.as_str_slice())
-    })
-}
-
 pub fn get_methods_if_impl(intr: Rc<IdentInterner>,
                                   cdata: Cmd,
                                   node_id: ast::NodeId)