Error overlay should show code for collapsed frames

[gaearon]

I think we should probably change the way collapsed frames work.
This is confusing because I don't see the actual place where the error happened, even if I expand:

I see my code immediately, which is valuable, but the error message makes full sense only in the context of the line that has thrown.

Ideally I think we should change the collapsed frames to also show the code, but they should be highlighted as a separate vertical block with its own distinct background. This way it’s also easier to keep track of where the collapsed section begins and ends.

[gaearon]

Maybe we should just avoid collapsing extra frames for TypeErrors since they're usually unexpected.