bindings: Add empty checks for toV8()

Source/bindings/templates/attributes.cpp

Index: Source/bindings/templates/attributes.cpp
diff --git a/Source/bindings/templates/attributes.cpp b/Source/bindings/templates/attributes.cpp
index cbd6355e99108f0b1791d680f20b3b638943113e..d1e9c6af832be89932b24f425dfd86744edd7bcc 100644
--- a/Source/bindings/templates/attributes.cpp
+++ b/Source/bindings/templates/attributes.cpp
@@ -435,6 +435,8 @@ bool {{v8_class}}::PrivateScript::{{attribute.name}}AttributeGetter(LocalFrame*
 
     ScriptState::Scope scope(scriptState);
     v8::Local<v8::Value> holder = toV8(holderImpl, scriptState->context()->Global(), scriptState->isolate());
+    if (holder.IsEmpty())
+        return false;
 
     ExceptionState exceptionState(ExceptionState::GetterContext, "{{attribute.name}}", "{{cpp_class}}", scriptState->context()->Global(), scriptState->isolate());
     v8::Local<v8::Value> v8Value = PrivateScriptRunner::runDOMAttributeGetter(scriptState, scriptStateInUserScript, "{{cpp_class}}", "{{attribute.name}}", holder);
@@ -465,6 +467,8 @@ bool {{v8_class}}::PrivateScript::{{attribute.name}}AttributeSetter(LocalFrame*
 
     ScriptState::Scope scope(scriptState);
     v8::Local<v8::Value> holder = toV8(holderImpl, scriptState->context()->Global(), scriptState->isolate());
+    if (holder.IsEmpty())
+        return false;
 
     ExceptionState exceptionState(ExceptionState::SetterContext, "{{attribute.name}}", "{{cpp_class}}", scriptState->context()->Global(), scriptState->isolate());
     return PrivateScriptRunner::runDOMAttributeSetter(scriptState, scriptStateInUserScript, "{{cpp_class}}", "{{attribute.name}}", holder, {{attribute.private_script_cpp_value_to_v8_value}});