[api] Restrict Template::Set to take templates or primitive values

Embedders that passed in non-primitive values should either use
getters/setters (templates) or install a native data property,
otherwise, the values would all result in cross-context leaks

BUG=none
R=verwaest@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/1839983002

Cr-Commit-Position: refs/heads/master@{#35244}

include/v8.h

@@ -4111,7 +4111,11 @@ enum Intrinsic {
  */
 class V8_EXPORT Template : public Data {
  public:
-  /** Adds a property to each instance created by this template.*/
+  /**
+   * Adds a property to each instance created by this template.
+   *
+   * The property must be defined either as a primitive value, or a template.
+   */
   void Set(Local<Name> name, Local<Data> value,
            PropertyAttribute attributes = None);
   V8_INLINE void Set(Isolate* isolate, const char* name, Local<Data> value);

src/api.cc

@@ -1028,13 +1028,13 @@ void Template::Set(v8::Local<Name> name, v8::Local<Data> value,
   ENTER_V8(isolate);
   i::HandleScope scope(isolate);
   auto value_obj = Utils::OpenHandle(*value);
+  CHECK(!value_obj->IsJSReceiver() || value_obj->IsTemplateInfo());
   if (value_obj->IsObjectTemplateInfo()) {
     templ->set_serial_number(i::Smi::FromInt(0));
     if (templ->IsFunctionTemplateInfo()) {
       i::Handle<i::FunctionTemplateInfo>::cast(templ)->set_do_not_cache(true);
     }
   }
-  // TODO(dcarney): split api to allow values of v8::Value or v8::TemplateInfo.
   i::ApiNatives::AddDataProperty(isolate, templ, Utils::OpenHandle(*name),
                                  value_obj,
                                  static_cast<i::PropertyAttributes>(attribute));