Check CallSite arguments more rigorously

src/wasm/wasm-module.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_WASM_MODULE_H_
 #define V8_WASM_MODULE_H_
 
 #include "src/wasm/wasm-opcodes.h"
 #include "src/wasm/wasm-result.h"
 
@@ skipping 302 matching lines @@
 // For testing. Decode, verify, and run the last exported function in the
 // given decoded module.
 int32_t CompileAndRunWasmModule(Isolate* isolate, const WasmModule* module);
 
 // Extract a function name from the given wasm object.
 // Returns a null handle if the function is unnamed or the name is not a valid
 // UTF-8 string.
 MaybeHandle<String> GetWasmFunctionName(Handle<JSObject> wasm,
                                         uint32_t func_index);
 
+// Check whether the given object is a wasm object.
+// This checks the number and type of internal fields, so it's not 100 percent
+// secure. If it turns out that we need more complete checks, we could add a
+// special marker as internal field, which will definitely never occur anywhere
+// else.
+bool IsWasmObject(Handle<JSObject> object);
+
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_MODULE_H_