Fix order of memory ops

Author: rossberg

interpreter/spec/decode.ml

@@ -284,10 +284,10 @@ let rec instr s =
 
   | 0x3f ->
     expect 0x00 s "zero flag expected";
-    grow_memory
+    current_memory
   | 0x40 ->
     expect 0x00 s "zero flag expected";
-    current_memory
+    grow_memory
 
   | 0x41 -> i32_const (at vs32 s)
   | 0x42 -> i64_const (at vs64 s)

interpreter/spec/encode.ml

@@ -209,8 +209,8 @@ let encode m =
       | Store ({ty = I64Type; sz = Some Mem32; _} as mo) -> op 0x3e; memop mo
       | Store {ty = F32Type | F64Type; sz = Some _; _} -> assert false
 
-      | GrowMemory -> op 0x3f; u8 0x00
-      | CurrentMemory -> op 0x40; u8 0x00
+      | CurrentMemory -> op 0x3f; u8 0x00
+      | GrowMemory -> op 0x40; u8 0x00
 
       | Const {it = I32 c; _} -> op 0x41; vs32 c
       | Const {it = I64 c; _} -> op 0x42; vs64 c