Patch to follow.
Created attachment 57257 [details] [PATCH] Proposed fix.
I was looking at this via Bug 39711 this morning. Guess we can close that. My fix was to add a call to this._refreshQueryString() in _refreshURL(). That worked for WebKit nightlies. I've also patched the WebCore/manual-tests/inspector/display-form-data.html test case to work better than it used to. It unfortunately can't really be run from a file:// url, and so would probably work better as a LayoutTest.
Created attachment 57261 [details] patch for manual test case current patch I was playing with - you won't want the ResourceView.js bit that's also in here, the rest is a patch to the manual test case
Comment on attachment 57257 [details] [PATCH] Proposed fix. Clearing flags on attachment: 57257 Committed r60327: <http://trac.webkit.org/changeset/60327>
All reviewed patches have been landed. Closing bug.