Print <undefined> in d8 when used as interactive shell.

Print <undefined> in d8 when used as interactive shell.

[Yang, 2011-08-26 07:57:17]

Something to consider as prompted by Andreas. This only changes the behavior of
the interactive shell, so running test cases is not affected by this change.

This is how it would look like, rather ugly imo:

yangguo@linea:~/localhome/v8$ ./d8
V8 version 3.5.9 (candidate) [console: dumb]
d8> var a
<undefined>
d8> a
<undefined>
d8> function a() { return 2}
<undefined>
d8> a
function a() { return 2}
d8> a() 
2
d8> void 0
<undefined>

[rossberg, 2011-08-26 10:44:14]

Yeah, I don't think this change is really useful as long as we cannot
distinguish between expressions and statements as input (I would only want to
see a result for the former). But that would probably be difficult to
incorporate.