Add scroll bar to integrated terminal

[bpasero]

On Mac I am not getting scrollbars when the content overflows.

[Tyriar]

Known issue, not sure scrollbars are going to happen unless we fork term.js.

[Tyriar]

Forking term.js would also be necessary if we wanted to do any improvements to the UX inside the terminal. For example improving the selection experience (related to this), adding links or something to terminal for tighter integration with editor (#1037), making the cursor blink without breaking selection, etc.

[bastienJS]

I use the integrated terminal only for doing "ng build" and getting an error message about what failed to build. But I am never able to read the cause of the failed build because I can not scroll up. Not every error is in the error windows. Sometimes error appear only at build process.

Thus if you want to justify the existance of the integrated terminal it really needs scrollbars or I have to the CMD.

[Tyriar]

@bastienJS you should still be able to scroll using the mouse wheel and ctrl+shift+arrows/page up/page down.