[gin] Allow interceptors to signal whether a they intercepted something

gin/interceptor.cc

Index: gin/interceptor.cc
diff --git a/gin/interceptor.cc b/gin/interceptor.cc
index 7efc32ee68bf2c82d6e03b4ae1fb5f99aa2b3284..617fd08e26d6108239cf2852902a32cdb2bd4139 100644
--- a/gin/interceptor.cc
+++ b/gin/interceptor.cc
@@ -26,9 +26,11 @@ v8::Local<v8::Value> NamedPropertyInterceptor::GetNamedProperty(
   return v8::Local<v8::Value>();
 }
 
-void NamedPropertyInterceptor::SetNamedProperty(v8::Isolate* isolate,
+bool NamedPropertyInterceptor::SetNamedProperty(v8::Isolate* isolate,
                                                 const std::string& property,
-                                                v8::Local<v8::Value> value) {}
+                                                v8::Local<v8::Value> value) {
+  return false;
+}
 
 std::vector<std::string> NamedPropertyInterceptor::EnumerateNamedProperties(
     v8::Isolate* isolate) {
@@ -51,10 +53,12 @@ v8::Local<v8::Value> IndexedPropertyInterceptor::GetIndexedProperty(
   return v8::Local<v8::Value>();
 }
 
-void IndexedPropertyInterceptor::SetIndexedProperty(
+bool IndexedPropertyInterceptor::SetIndexedProperty(
     v8::Isolate* isolate,
     uint32_t index,
-    v8::Local<v8::Value> value) {}
+    v8::Local<v8::Value> value) {
+  return false;
+}
 
 std::vector<uint32_t> IndexedPropertyInterceptor::EnumerateIndexedProperties(
     v8::Isolate* isolate) {