Basic experimental suborigin CSP directive and SecurityOrigin mods

Source/core/dom/Document.h

Index: Source/core/dom/Document.h
diff --git a/Source/core/dom/Document.h b/Source/core/dom/Document.h
index ea7f64e3b762cbcff13cb65f18ba956eacbf15b6..1564b609d9bab8e6247587962548a11734440f8f 100644
--- a/Source/core/dom/Document.h
+++ b/Source/core/dom/Document.h
@@ -1080,7 +1080,7 @@ private:
     bool isElementNode() const = delete; // This will catch anyone doing an unnecessary check.
 
     ScriptedAnimationController& ensureScriptedAnimationController();
-    virtual const SecurityContext& securityContext() const override final { return *this; }
+    virtual SecurityContext& securityContext() override final { return *this; }
     virtual EventQueue* eventQueue() const override final;
 
     // FIXME: Rename the StyleRecalc state to LayoutTreeUpdate.