Fold throw_ref too

Author: SoniEx2

test/roundtrip/fold-unreachable.txt

@@ -1,5 +1,5 @@
 ;;; TOOL: run-roundtrip
-;;; ARGS: --stdout --fold-exprs
+;;; ARGS: --stdout --enable-exceptions --fold-exprs
 (module
   (func (result i32)
     i32.const 1
@@ -26,7 +26,12 @@
   (func (result i32)
     i32.const 0
     return
-    i32.eqz))
+    i32.eqz)
+
+  (func
+    ref.null exn
+    throw_ref
+  ))
 (;; STDOUT ;;;
 (module
   (type (;0;) (func (result i32)))
@@ -50,5 +55,8 @@
   (func (;3;) (type 0) (result i32)
     (i32.eqz
       (return
-        (i32.const 0)))))
+        (i32.const 0))))
+  (func (;4;) (type 1)
+    (throw_ref
+      (ref.null exn))))
 ;;; STDOUT ;;)