Fix slash in Windows build instructions

This could be mildly confusing to some who are unfamiliar with using bash.
Upgrade to grammar-selector@0.27.0
Support core:move-up/down in ScrollView

Closes #1828
Add displayName to ScrollbarComponent and ScrollbarCornerComponent
Run react perf in scroll benchmark if NODE_ENV isn't production
Merge pull request #2362 from CoolOppo/patch-1

Fix slash in Windows build instructions
Merge pull request #2368 from atom/iz-scrollview-support-for-core-move-up-down

Support core:move-up and core:move-down in ScrollView