```
ext.RevisionSlider.DiffPage
✔ Initialize DiffPage
✖ Push state
FAILED TESTS:
ext.RevisionSlider.DiffPage
✖ Push state
HeadlessChrome 0.0.0 (Linux 0.0.0)
Expected: 2
Actual: 1
at Object.<anonymous> (http://localhost:9876/load.php?debug=false&lang=en&modules=color-picker%2CdiffMatchPatch%2Cdompurify%7Cext.RevisionSlider.DiffPage%2CHelpDialog%2CPointer%2CPointerLine%2CPointerView%2CRevision%2CRevisionList%2CRevisionListView%2CSlider%2CSliderView%2CdialogImages%2Ctests%2Cutil%7Cext.centralauth.ForeignApi%7Cext.centralauth.ForeignApi.test%7Cext.cite.style%2Cstyles%2CvisualEditor%7Cext.cite.visualEditor.core%2Cdata%2Cicons%2Ctest%7Cext.echo.api%2Cdm%7Cext.echo.dm.tests%7Cext.eventLogging%7Cext.eventLogging.subscriber%2Ctests%7Cext.visualEditor.articleTarget%2Cbase%2CcommentAnnotation%2Ccore%2Cdata%2CdesktopArticleTarget%2CdesktopTarget%2Cdiffing%2Cexperimental%2Cicons%2Clanguage%2Cmediawiki%2CmoduleIcons%2Cmwalienextension%2Cmwcore%2Cmwextensionmessages%2Cmwextensions%2Cmwformatting%2Cmwgallery%2Cmwimage%2Cmwlanguage%2Cmwlink%2Cmwmeta%2Cmwsave%2Cmwtransclusion%2Crebase%2Csanitize%2CsupportCheck%2Cswitching%2CtargetLoader%2CtempWikitextEditorWidget%2Ctest%2Ctrack%2Cve%2Cwelcome%7Cext.visualEditor.core.desktop%7Cext.visualEditor.desktopArticleTarget.init%7Cext.visualEditor.mwextensions.desktop%7Cext.visualEditor.mwimage.core%7Cext.wikiEditor.toolbar.test%7Cjquery.accessKeyLabel%2Casync%2CcheckboxShiftClick%2Cclient%2Ccolor%2CcolorUtil%2Ccookie%2CgetAttrs%2Chidpi%2ChighlightText%2ClengthLimit%2Clocalize%2CmakeCollapsible%2Csuggestions%2CtabIndex%2Ctablesorter%2CtextSelection%2Cthrottle-debounce%7Cjquery.makeCollapsible.styles%7Cjquery.uls.data%7Cmediawiki.ForeignApi%2CForeignStructuredUpload%2CForeignUpload%2CRegExp%2CString%2CTitle%2CUpload%2CUri%2Capi%2Ccldr%2CconfirmCloseWindow%2Ccookie%2Cexperiments%2Cinspect%2CjqueryMsg%2Clanguage%2CmessagePoster%2Cnotification%7Cmediawiki.ForeignApi.core%7Cmediawiki.ForeignStructuredUpload.BookletLayout%2Cconfig%7Cmediawiki.Upload.BookletLayout%2CDialog%7Cmediawiki.action.view.redirectPage%7Cmediawiki.diff.styles%7Cmediawiki.editfont.styles%7Cmediawiki.language.data%2Cinit%2Cmonths%2Cnames%2CspecialCharacters%7Cmediawiki.libs.jpegmeta%2Cpluralruleparser&skin=vector&version=19bq1ik:141:439)
at runTest (node_modules/qunit/qunit/qunit.js:1530:30)
at Test.run (node_modules/qunit/qunit/qunit.js:1516:6)
at node_modules/qunit/qunit/qunit.js:1728:12
at advanceTaskQueue (node_modules/qunit/qunit/qunit.js:1129:6)
at advance (node_modules/qunit/qunit/qunit.js:1110:4)
```
Spotted via the experimental Quibble job by commenting `check experimental` on a dummy change: https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/RevisionSlider/+/363822/
The job runs in a Docker container that has Chrome v66.
Locally, the test passes with Firefox 52 and fail with `Chrome 66.0.3359`:
{F22664047 size=full}