Revert "Handle conditionals on _|_ - typed values correctly"

This reverts commit 13f8b3f2a6.

run-pass/if-ret.rs does not translate correctly when unoptimized. Issue #797

src/comp/middle/trans.rs

@@ -3592,18 +3592,6 @@ fn trans_if(cx: &@block_ctxt, cond: &@ast::expr, thn: &ast::blk,
             els: &option::t[@ast::expr], id: ast::node_id,
             output: &out_method) -> result {
     let cond_res = trans_expr(cx, cond);
-
-    if (ty::type_is_bot(bcx_tcx(cx), ty::expr_ty(bcx_tcx(cx), cond))) {
-        // No need to generate code for comparison,
-        // since the cond diverges.
-        if (!cx.build.is_terminated()) {
-            ret rslt(cx, cx.build.Unreachable());
-        }
-        else {
-            ret rslt(cx, C_nil());
-        }
-    }
-
     let then_cx = new_scope_block_ctxt(cx, "then");
     let then_res = trans_block(then_cx, thn, output);
     let else_cx = new_scope_block_ctxt(cx, "else");

src/test/run-fail/if-cond-bot.rs

@@ -1,3 +0,0 @@
-// error-pattern:quux
-fn my_err(s: str) -> ! { log_err s; fail "quux"; }
-fn main() { if my_err("bye") { } }