ObjectHandlers that change the object type fail guard checks when using dot notation

[spullara]

The example we have is the ScalaObjectHandler wraps Scala Maps with a Java Map compatible class. However, if you use dot notation to access the map we fail a guard check as the type is incompatible when it checks it later. Clearly a bug in the dot notation code.

#188

[spullara]

It took me a bit to figure out exactly what was going on here but finally tracked it down.

81cc33f