1. A method, implemented at a computer system that includes one or more processors, for communicating an object between frames of a web browser window, the method comprising: at a source frame within a browser window, identifying a source object of a first object type is to be sent from the source frame over an inter-frame communication channel to a target frame within the browser window, wherein the source frame is configured to convert the source object to a transport-compatible type that is used by the inter-frame communication channel prior to sending the source object over the inter-frame communication channel; at the source frame, identifying that the target frame is incapable of converting data of the transport-compatible type into objects of the first object type; and at the source frame, and based at least on identifying that the target frame is incapable of converting data of the transport type into objects of the first object type: identifying a second object type that the target frame is capable of converting data of the transport type into; restructuring the source object to be a restructured object of the second object type, wherein the restructured object includes encoded source type information that correlates to the first object type; converting the restructured object from the second object type to a transport-compatible object of the transport-compatible type; and sending the transport-compatible object over the inter-frame communication channel to the target frame, wherein, based on the source frame having sent the transport-compatible object over the inter-frame communication channel to the target frame, the target frame is configured to convert the transport-compatible object into an object of the second object type that preserves the encoded source type information, and to use the encoded source type information to restructure the object of the second object type into a target object of the first type that corresponds to the source object.