[wasm] Indirect calls without function table cause validation errors.

src/wasm/signature-map.h

Index: src/wasm/signature-map.h
diff --git a/src/wasm/signature-map.h b/src/wasm/signature-map.h
index 28c9fd63edee258f5531ba3649f18dd90e48109c..3a7ed0a0479991783f01e669ed8278464874b581 100644
--- a/src/wasm/signature-map.h
+++ b/src/wasm/signature-map.h
@@ -17,7 +17,7 @@ namespace wasm {
 // A signature map canonicalizes signatures into a range of indices so that
 // two different {FunctionSig} instances with the same contents map to the
 // same index.
-class SignatureMap {
+class V8_EXPORT_PRIVATE SignatureMap {
  public:
   // Gets the index for a signature, assigning a new index if necessary.
   uint32_t FindOrInsert(FunctionSig* sig);