User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:61.0) Gecko/20100101 Firefox/61.0 Build ID: 20180704003137 Steps to reproduce: Clarifications about the fallback value of the Visual Viewport API have been made to the spec [1]. We would like to test if the situations discussed in the spec issue have been correctly addressed by the current implementation of the Visual Viewport API and update the fallback values accordingly. [1] https://github.com/WICG/visual-viewport/issues/56

To clarify the previous comment, this bug tracks an update to a feature and not a crash/bug in the Firefox build mentioned.(In reply to Tanushree Podder [:tanushree] from comment #0) > User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:61.0) > Gecko/20100101 Firefox/61.0 > Build ID: 20180704003137 > > Steps to reproduce: >

(In reply to Tanushree Podder [:tanushree] from comment #0) > Clarifications about the fallback value of the Visual Viewport API have been > made to the spec [1]. Note, the changes to the spec have not been made yet. They have been discussed in the linked issue, and the proposed changes can be found in this PR: https://github.com/WICG/visual-viewport/pull/58

The spec changes have been merged. On the question of "scale", the algorithm in the spec for computing it now begins like so: 1. If the window's associated Document is not fully active, return 0 and abort these steps. 2. If there is no output device, return 1 and abort these steps. ... which suggests that there should be two different "early-return" conditions which return 0 and 1, respectively. It's not clear to me which of the above spec conditions the current conditions of the early-return in the implementation (the window, doc shell, or pres shell being null) correspond to, or even whether both of the spec conditions can necessarily occur in Firefox (for example, regarding the "no output device" condition, David mentions [1] that it may be intended to cover a "headless mode", but as far as I'm aware, to the extent that Firefox has a headless mode [2], objects like pres shells are still created and calculations such as computing pixel ratios still happen in that mode). Any insights / clarifications on this topic would be appreciated. [1] https://github.com/WICG/visual-viewport/issues/56#issuecomment-417804540 [2] https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Headless_mode