adjust for wasm-demo

src/wasm/ast-decoder.h

Index: src/wasm/ast-decoder.h
diff --git a/src/wasm/ast-decoder.h b/src/wasm/ast-decoder.h
index f07c8800f80a468bbe578f39682a1c043beff17d..6f5acfba2d59a466309827c72a12233d7f1b6a8b 100644
--- a/src/wasm/ast-decoder.h
+++ b/src/wasm/ast-decoder.h
@@ -107,6 +107,15 @@ struct BlockCountOperand {
   uint32_t count;
   int length;
   inline BlockCountOperand(Decoder* decoder, const byte* pc) {
+    count = decoder->checked_read_u32(pc, 1, "block count");
+    length = 4;
+  }
+};
+
+struct LoopCountOperand {
+  uint32_t count;
+  int length;
+  inline LoopCountOperand(Decoder* decoder, const byte* pc) {
     count = decoder->checked_read_u8(pc, 1, "block count");
     length = 1;
   }