Deduplicate StripProto methods

Author: georgthegreat

src/google/protobuf/compiler/js/js_generator.cc

@@ -99,15 +99,6 @@ bool StrEndsWith(StringPiece sp, StringPiece x) {
   return sp.size() >= x.size() && sp.substr(sp.size() - x.size()) == x;
 }
 
-// Returns a copy of |filename| with any trailing ".protodevel" or ".proto
-// suffix stripped.
-// TODO(haberman): Unify with copy in compiler/cpp/internal/helpers.cc.
-std::string StripProto(const std::string& filename) {
-  const char* suffix =
-      StrEndsWith(filename, ".protodevel") ? ".protodevel" : ".proto";
-  return StripSuffixString(filename, suffix);
-}
-
 std::string GetSnakeFilename(const std::string& filename) {
   std::string snake_name = filename;
   ReplaceCharacters(&snake_name, "/", '_');