UX scroll tests

[jiku]

I.e. as part of UX (cutaneous) (using xolvio/chimp, but could maybe migrate to Cypress). Then Chimp again for acceptance/E2E, integration, tests that tie into that.

Aspects to cover

• Inter-site history ... (for X, maybe Intra-site history not scrolling #49, Inter-site navigation doesn't scroll to correct position (section) #51)
• Intra-site history ... (for Intra-site history not scrolling #49)
• Extra-site links ... (for Inter-site navigation doesn't scroll to correct position (section) #51, Section entry broken in Chrome (49 on OSX 10.10.5) #83)
• Intra-site links ...
• Menu ...
• Manual scroll ...

... scrolls to element position, updates URI and triggers correct events

Worked before, but now

    Then the app scrolls to the footer section
      Error: Promise was rejected with the following reason: TypeError: this.execute(...).then is not a function

      Error: element (body) still not existing after 500ms