[wasm] Fix bug with empty input to Wasm.instantiateModuleFromAsm()

src/wasm/wasm-js.cc

Index: src/wasm/wasm-js.cc
diff --git a/src/wasm/wasm-js.cc b/src/wasm/wasm-js.cc
index 833c39902559e4d86bea1a1b82e27282d6a97b6e..0992031e45a07aa5f65a422709a85b0ce28f2c8b 100644
--- a/src/wasm/wasm-js.cc
+++ b/src/wasm/wasm-js.cc
@@ -134,6 +134,11 @@ v8::internal::wasm::WasmModuleIndex* TranslateAsmModule(
     return nullptr;
   }
 
+  if (info->scope()->declarations()->length() == 0) {
+    thrower->Error("Asm.js validation failed: no declarations in scope");
+    return nullptr;
+  }
+
   info->set_literal(
       info->scope()->declarations()->at(0)->AsFunctionDeclaration()->fun());