remove usage of feature gate

src/librustc/lib.rs

@@ -50,7 +50,6 @@
 #![feature(thread_local)]
 #![feature(trace_macros)]
 #![feature(trusted_len)]
-#![feature(vec_remove_item)]
 #![feature(stmt_expr_attributes)]
 #![feature(integer_atomics)]
 #![feature(test)]

src/librustdoc/lib.rs

@@ -10,7 +10,6 @@
 #![feature(nll)]
 #![feature(set_stdio)]
 #![feature(test)]
-#![feature(vec_remove_item)]
 #![feature(ptr_offset_from)]
 #![feature(crate_visibility_modifier)]
 #![feature(const_fn)]

src/tools/compiletest/src/main.rs

@@ -1,6 +1,5 @@
 #![crate_name = "compiletest"]
 #![feature(test)]
-#![feature(vec_remove_item)]
 #![deny(warnings)]
 
 extern crate test;