Test fixes and rebase conflicts, round 2

Conflicts:
	src/libcore/num/mod.rs

src/test/compile-fail/const-eval-overflow.rs

@@ -11,6 +11,7 @@
 #![feature(negate_unsigned)]
 
 #![allow(unused_imports)]
+#![feature(negate_unsigned)]
 
 // Note: the relevant lint pass here runs before some of the constant
 // evaluation below (e.g. that performed by trans and llvm), so if you

src/test/compile-fail/lint-exceeding-bitshifts.rs

@@ -12,7 +12,7 @@
 #![deny(exceeding_bitshifts)]
 #![allow(unused_variables)]
 #![allow(dead_code)]
-#![feature(core)]
+#![feature(core, negate_unsigned)]
 
 fn main() {
       let n = 1u8 << 7;

src/test/compile-fail/lint-type-limits.rs

@@ -10,6 +10,7 @@
 
 #![feature(negate_unsigned)]
 #![allow(dead_code)]
+#![feature(negate_unsigned)]
 
 // compile-flags: -D unused-comparisons
 fn main() { }