Warnings on b-form-select open/close in recent Chrome

To recreate: Go to https://bootstrap-vue.js.org/play/ in Chrome v66 (I believe v51 or newer) and enter the following template:

  <b-form-select>
      <option>Sample</option>
  </b-form-select>

Then open and close the resulting select input several times.

Expected: Developer console free of warnings and errors.

Actual: See the following warning in the JavaScript console:

[Violation] Added non-passive event listener to a scroll-blocking ‘mousewheel’ event. Consider marking event handler as ‘passive’ to make the page more responsive. See https://www.chromestatus.com/feature/5745543795965952

[tmorehouse]

I think it might be docs use of v-b-scroll-spy directive… which monitors the page scrolling to highlight the current page section TOC (on the right hand side).

We’ll have to update our eventOn handler to detect support of the passive option (not all browsers support it, and if present treat it as wanting to use capture mode).

Will see what we can do over the next week.

[tmorehouse]

My work laptop still has chrome v60 (can’t update it as it is controlled by work IT department), and I see the warning crop up once and a while.