Clean up for ES2015 transforms#13040

Merged

rbuckton merged 3 commits intomasterfrom

Dec 23, 2016

Commits on Dec 8, 2016

Simplify es2015 visitor, replace function tracking with flags
rbuckton
committed

Commits on Dec 19, 2016

Merge branch 'master' into es2015-cleanup
rbuckton
committed

Commits on Dec 20, 2016

Improve hierarchy fact tracking
rbuckton
committed