Updated .gitignore to ignore sandbox test directory
Fixed styling for top and bottom margin mostly (except for toggle).
TESTING in simple page
Removed TEST.  Fixed toggle issue by creating a third layer.  Now Outline contains outline and toggle button, outlineContent contains just the outline content and outlineScrollable contains just the scrolling component (as opposed to the container with margins).  Because toggle button needs to turn only the margin container off, had to separate).  Also, fixed vertical scrollbar hiding.
Reverted spacing change
removed duplicate widths and background colors
Fixed margins so scrollbar shows up on right side with no margin gap.
Merge pull request #1406 from dart-lang/umop-outline-vertical_spacing

Outline vertical spacing (margins) and scrollbar visibility.