Cherry-pick PR microsoft#37510 into release-3.9

Component commits:
b9a7fe0 Fix import order

Author: falsandtru

src/lib/es2015.d.ts

@@ -1,9 +1,9 @@
 /// <reference lib="es5" />
 /// <reference lib="es2015.core" />
 /// <reference lib="es2015.collection" />
+/// <reference lib="es2015.iterable" />
 /// <reference lib="es2015.generator" />
 /// <reference lib="es2015.promise" />
-/// <reference lib="es2015.iterable" />
 /// <reference lib="es2015.proxy" />
 /// <reference lib="es2015.reflect" />
 /// <reference lib="es2015.symbol" />

src/lib/es2018.d.ts

@@ -1,6 +1,6 @@
 /// <reference lib="es2017" />
-/// <reference lib="es2018.asyncgenerator" />
 /// <reference lib="es2018.asynciterable" />
+/// <reference lib="es2018.asyncgenerator" />
 /// <reference lib="es2018.promise" />
 /// <reference lib="es2018.regexp" />
 /// <reference lib="es2018.intl" />