Revert "librustc: Make unqualified identifier searches terminate at the nearest module scope. r=tjc"

This reverts commit a8d37af247.

src/libsyntax/parse/common.rs

@@ -8,16 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use core::prelude::*;
-
 use ast;
 use ast_util::spanned;
-use codemap::BytePos;
 use parse::lexer::reader;
 use parse::parser::Parser;
 use parse::token;
 
-use core::option::{None, Option, Some};
 use core::option;
 use std::map::HashMap;