[profile-viewer] allow core and package times to be collapsed into app times

[pmuellr]

It would be nice to consider app function times to include core function time, and probably other package function time. Eg, if an app function is using an expensive RegExp, or JSON.parse(), it would be nice to do the time accounting for the function using these, to that function itself.

I think this would just affect the time values, and nothing else.

I think the way this would work is that we'd look a function in the stack, and if it's an app function, any functions it calls that we'd want to collapse (core, or all non-app packages), we'd add it's self time to the function, and then recurse on that stack, eating subsequent collapsible entries.

In the case where a stack starts in a collapsible function, then all the collapsible functions up to the first non-collapsible would be added to that non-collapsible function.

What about stacks that only contain collapsible functions? I don't think there's anything we can do about those :-)