URL: https://www.google.com/
Browser / Version: Firefox 50.0
Operating System: Android 4.4.4
Problem type: Something else - I'll add details below

Steps to Reproduce

1. fake the user agent to be chrome
2. switched off webkit css rewriting stuff.
   about:config?filter=layout.css.prefixes.webkit -> false
3. switched off the unprefixing service
   about:config?filter=unprefixing-service.enabled -> false
4. Navigate to: https://www.google.com/
5. type "dog", switch to "images".

Expected Behavior:
Having the images search being displayed

Actual Behavior:
The images appeared quickly and disappears right away.

This is part of testing Google on Firefox Gecko when faking the UA.

Some issues for probably Edge and Firefox implementing WebKit stuff. Here and there the CSS contains things like:

    border-radius:0 0 3px 3px;
    -webkit-border-radius:0 0 3px 3px;
    box-shadow:0 2px 1px rgba(0,0,0,.1), 0 0 1px rgba(0,0,0,.1);
    -webkit-box-shadow:0 2px 1px rgba(0,0,0,.1), 0 0 1px rgba(0,0,0,.1);

where the -webkit- is defined after the standard property.

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