[wasm] Fix for 608630: allow proxies as FFI.

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.h"
 #include "src/api-natives.h"
 #include "src/assert-scope.h"
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/factory.h"
@@ skipping 167 matching lines @@
   i::Zone zone(isolate->allocator());
   internal::wasm::ModuleResult result = internal::wasm::DecodeWasmModule(
       isolate, &zone, start, end, false, origin);
 
   if (result.failed() && origin == internal::wasm::kAsmJsOrigin) {
     thrower->Error("Asm.js converted module failed to decode");
   } else if (result.failed()) {
     thrower->Failed("", result);
   } else {
     // Success. Instantiate the module and return the object.
-    i::Handle<i::JSObject> ffi = i::Handle<i::JSObject>::null();
+    i::Handle<i::JSReceiver> ffi = i::Handle<i::JSObject>::null();
     if (args.Length() > 1 && args[1]->IsObject()) {
       Local<Object> obj = Local<Object>::Cast(args[1]);
-      ffi = i::Handle<i::JSObject>::cast(v8::Utils::OpenHandle(*obj));
+      ffi = i::Handle<i::JSReceiver>::cast(v8::Utils::OpenHandle(*obj));
     }
 
     i::MaybeHandle<i::JSObject> object =
         result.val->Instantiate(isolate, ffi, memory);
 
     if (!object.is_null()) {
       args.GetReturnValue().Set(v8::Utils::ToLocal(object.ToHandleChecked()));
     }
   }
 
@@ skipping 129 matching lines @@
     int unused_property_fields = in_object_properties - pre_allocated;
     Handle<Map> map = Map::CopyInitialMap(
         prev_map, instance_size, in_object_properties, unused_property_fields);
 
     context->set_wasm_function_map(*map);
   }
 }
 
 }  // namespace internal
 }  // namespace v8