HTML Element changing from position: fixed to position: sticky crashes webkit process (or renders incorrectly)

Originator:oliver.byford
Number:rdar://29459895 Date Originated:1 Dec 2016
Status:Duplicate/27831095 Resolved:
Product:iOS + SDK Product Version:10.1
Classification: Reproducible:
 
Area:
WebKit

Summary:
When an HTML element that was previously of type `position: fixed;` is changed to type `position: sticky;` it either crashes the Webkit process or is rendered incorrectly by Webkit browsers on iOS.

Steps to Reproduce:
1. Load the 'open' example (open.html) in an iOS browser.
2. Click the 'Show / Hide Table of Contents' toggle link

Expected Results:
The nav reverts to stick at the top of the screen, as in the initial state of the 'closed' example.

Actual Results:
The web content process will usually (but not always) crash. If it does not crash, the element reverts to its sticky state, but is not stuck at the right place, and occasionally seems to disappear entirely.

Version:
iOS 10.1 (14B72), Safari or Chrome 54.0.2840.91

Notes:
Hosted version of example available at https://36degrees.github.io/webkit-ios-fixed-sticky/

This also happens in Safari 10.0 (12602.1.50.0.10) on macOS 10.12 (16A323), submitted as a separate bug report (with Web Content Crash Dump)

Configuration:
iPhone 6s

Comments


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