Variable length array of non-POD element type is not valid

src/js/bridge.cpp (NativeClass::staticOperation, NativeClass::constructor): Change invalid variadic arrays to alloca based implementation
src/v8/bridgeV8.cpp (NativeClass::staticOperation, NativeClass::constructor, ProxyObject::message_): Change invalid variadic arrays to alloca based implementation
(TemporaryBuffer): New based on AllocaOwner