Fix op_unless coercion

Sample code:
```
my $foo := 42;
my int $bar := $foo || 200;
say($bar);
```

Before it says '0' and now '42'.
The problem is we generate $foo || 200 as

- QAST::Op(unless &infix:<||>)  ||
  - QAST::Var(lexical $bar)
  - QAST::IVal(200)

and thus $bar only be a condition. If we want to return its value,
we forget to coerce its kind.

Now this fix only apply on op_unless. If applies on the four ops
handled this block, it fails some tests in t/qast/01-qast.t.

src/vm/moar/QAST/QASTOperationsMAST.nqp

@@ -807,6 +807,7 @@ for <if unless with without> -> $op_name {
             );
         }
 
+        my $fix_coercion;
         # Emit the then, stash the result
         push_ilist(@ins, @comp_ops[1]);
         if (!$is_void && @comp_ops[1].result_kind != $res_kind) {
@@ -817,6 +818,14 @@ for <if unless with without> -> $op_name {
             $res_reg := $regalloc.fresh_register($coercion.result_kind);
             push_op(@ins, 'set', $res_reg, $coercion.result_reg);
             $res_kind := $coercion.result_kind;
+            if ($op_name eq 'unless' && $operands == 2 && @comp_ops[0].result_kind != $res_kind) {
+                my $coercion := $qastcomp.coercion(@comp_ops[0],
+                    (nqp::defined($*WANT) ?? $*WANT !! $MVM_reg_obj));
+                $fix_coercion := $coercion;
+                $regalloc.release_register($res_reg, $res_kind);
+                $res_reg := $regalloc.fresh_register($coercion.result_kind);
+                $res_kind := $coercion.result_kind;
+            }
         }
         elsif !$is_void {
             push_op(@ins, 'set', $res_reg, @comp_ops[1].result_reg);
@@ -845,6 +854,11 @@ for <if unless with without> -> $op_name {
         $regalloc.release_register(@comp_ops[0].result_reg, @comp_ops[0].result_kind);
         nqp::push(@ins, $end_lbl);
 
+        if $fix_coercion {
+          push_ilist(@ins, $fix_coercion);
+          push_op(@ins, 'set', $res_reg, $fix_coercion.result_reg);
+        }
+
         MAST::InstructionList.new(@ins, $res_reg, $res_kind)
     });
 }

t/qast/01-qast.t

@@ -651,7 +651,7 @@ test_qast_result(
     -> $r {
         ok(nqp::getattr_i($r, E, '$!x') == 99, 'attribute binding works');
     });
-    
+
 my $test_obj := nqp::create(E);
 nqp::bindattr_i($test_obj, E, '$!x', 199);
 is_qast_args(
@@ -1392,9 +1392,9 @@ test_qast_result(
                 ),
                 sval('D')
            ),
-           QAST::Op.new( :op<chain>, :name<op1>, 
+           QAST::Op.new( :op<chain>, :name<op1>,
                QAST::Op.new( :op<chain>, :name<op2>,
-                   QAST::Op.new( :op<chain>, :name<op3>, 
+                   QAST::Op.new( :op<chain>, :name<op3>,
                        QAST::Op.new( :op<chain>, :name<op2>, sval('A'), sval('B')),
                        sval('E')
                    ),
@@ -2172,7 +2172,7 @@ is_qast(
                         with_arity(1, QAST::Block.new(
                             :blocktype<immediate>,
                             QAST::Op.new(
-                                :op<if>, 
+                                :op<if>,
                                 QAST::Op.new(
                                     :op<iseq_i>,
                                     QAST::Var.new( :name('$j'), :scope<lexical>, :decl<param> ),