Make .prototype properties of Wasm constructors read-only

src/wasm/wasm-js.cc

 // 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.
 
 #include "src/api-natives.h"
 #include "src/api.h"
 #include "src/asmjs/asm-js.h"
 #include "src/asmjs/asm-typer.h"
 #include "src/asmjs/asm-wasm-builder.h"
 #include "src/assert-scope.h"
@@ skipping 548 matching lines @@
   v8::ReturnValue<v8::Value> return_value = args.GetReturnValue();
   return_value.Set(Utils::ToLocal(buffer));
 }
 }  // namespace
 
 // TODO(titzer): we use the API to create the function template because the
 // internal guts are too ugly to replicate here.
 static i::Handle<i::FunctionTemplateInfo> NewTemplate(i::Isolate* i_isolate,
                                                       FunctionCallback func) {
   Isolate* isolate = reinterpret_cast<Isolate*>(i_isolate);
-  Local<FunctionTemplate> local = FunctionTemplate::New(isolate, func);
-  return v8::Utils::OpenHandle(*local);
+  Local<FunctionTemplate> templ = FunctionTemplate::New(isolate, func);
+  templ->ReadOnlyPrototype();
+  return v8::Utils::OpenHandle(*templ);
 }
 
 namespace internal {
 
 Handle<JSFunction> InstallFunc(Isolate* isolate, Handle<JSObject> object,
                                const char* str, FunctionCallback func,
                                int length = 0) {
   Handle<String> name = v8_str(isolate, str);
   Handle<FunctionTemplateInfo> temp = NewTemplate(isolate, func);
   Handle<JSFunction> function =
@@ skipping 186 matching lines @@
   i::Handle<i::Symbol> symbol(isolate->context()->wasm_memory_sym(), isolate);
   return HasBrand(value, symbol);
 }
 
 bool WasmJs::IsWasmTableObject(Isolate* isolate, Handle<Object> value) {
   i::Handle<i::Symbol> symbol(isolate->context()->wasm_table_sym(), isolate);
   return HasBrand(value, symbol);
 }
 }  // namespace internal
 }  // namespace v8