Convert page-related unit tests to ES6 and clean up some existing tests.

Review Request #9162 - Created Aug. 30, 2017 and submitted

Christian Hammond
Review Board

This converts the JavaScript unit tests for RB.DiffViewerPageView and
RB.ReviewablePageView to ES6, in preparation for a new set of tests
coming in.

The tests for RB.ReviewRequestPageView have been fixed to use
function() {} instead of () => {} for Jasmine tests, since the
former is recommended (due to Jasmine populating this with state, and
the ability for test suites to store their own local state in Jasmine's
this). It also fixes a variable name (page to pageView), which
will help with future tests.

All unit tests pass.

Christian Hammond
David Trowbridge
Christian Hammond
Review request changed

Status: Closed (submitted)

Change Summary:

Pushed to release-3.0.x (42fa79f)