message: update changelog prior to new version release.
diff: +## X.Y.Z (INSERT_DATE_HERE)
  +
  +#### Bug Fixes
  +
  +- [Performance regressions in Chrome Beta (74)](https://github.com/SAP/chevrotain/issues/942)
  +
  ## 4.3.2 (4-2-2019)
  #### Bug Fixes
  