[GTK] "Console: undefined @0: ReferenceError: Can't find variable: WebInspector"...

[GTK] "Console: undefined @0: ReferenceError: Can't find variable: WebInspector" during testwebinspector
https://bugs.webkit.org/show_bug.cgi?id=80235

Reviewed by Philippe Normand.

Source/WebKit/gtk:

Wait to inspect the WebView until the page has finished loading. Also
clean up some minor style errors.

* tests/testwebinspector.c:
(closeInspector): Small style fixes.
(showInspector): Ditto.
(loadFinished): Ditto.
(test_webkit_web_inspector_close_and_inspect): Wait to inspect until the page has loaded.
(test_webkit_web_inspector_destroy_inspected_web_view): Ditto.
(main): Small style fixes.

Tools:

* Scripts/run-gtk-tests:
(TestRunner.run): Use the WEBKIT_INSPECTOR_PATH environment variable so that
inspector resources path determination is shared by all tests.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@109720 268f45cc-cd09-0410-ab3c-d52691b4dbfc