[GTK] Test TestWebKitAPI/WebKit2Gtk/TestInspectorServer fails

[GTK] Test TestWebKitAPI/WebKit2Gtk/TestInspectorServer fails
https://bugs.webkit.org/show_bug.cgi?id=132044

Reviewed by Brian Burg.

Source/WebInspectorUI:

Make sure Protocol/InspectorFrontendHostStub.js is loaded before
Base/Platform.js, because Platform uses the InspectorFrontendHost
object.

* UserInterface/Main.html:

Tools:

* TestWebKitAPI/Tests/WebKit2Gtk/TestInspectorServer.cpp:
(openRemoteDebuggingSession): Remove trailing slash when
concatenating base inspector URL with the page, because the
inspector returns the relative paths with a leading slash.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@174926 268f45cc-cd09-0410-ab3c-d52691b4dbfc