TEMP
Merge branch 'master' of https://github.com/dart-lang/spark into umop-markers-zoom
Merge branch 'master' of https://github.com/dart-lang/spark into umop-markers-zoom
Merge branch 'master' of https://github.com/dart-lang/spark into umop-markers-zoom
TEMP
Resolved conflicts
Markers now display correctly when not scrolling
Moved scrolling / not scrolling logic out of main loop for performance.
Clean up
Merge pull request #1799 from dart-lang/umop-markers-zoom

Correct placement of markers when not scrolling