Fix: findSection for IE11 (#1004)
Fix: findSection for IE11 (#1004)

Fixes #1003
sapegin/react-styleguidist,styleguidist/react-styleguidist,styleguidist/react-styleguidist,styleguidist/react-styleguidist,sapegin/react-styleguidist,bluetidepro/react-styleguidist