Mixed Content: Implement strict mode.

Source/core/dom/ExecutionContext.h

Index: Source/core/dom/ExecutionContext.h
diff --git a/Source/core/dom/ExecutionContext.h b/Source/core/dom/ExecutionContext.h
index 6decfb99508f6db8a091a40f09768bd144d571bd..daf2172090d2ffd8344f385334d5884f0d19988c 100644
--- a/Source/core/dom/ExecutionContext.h
+++ b/Source/core/dom/ExecutionContext.h
@@ -133,6 +133,9 @@ public:
     virtual EventTarget* errorEventTarget() = 0;
     virtual EventQueue* eventQueue() const = 0;
 
+    void enforceStrictMixedContentChecking() { m_strictMixedContentCheckingEnforced = true; }
+    bool shouldEnforceStrictMixedContentChecking() const { return m_strictMixedContentCheckingEnforced; }
+
 protected:
     ExecutionContext();
     virtual ~ExecutionContext();
@@ -173,6 +176,8 @@ private:
 
     OwnPtrWillBeMember<PublicURLManager> m_publicURLManager;
 
+    bool m_strictMixedContentCheckingEnforced;
+
     // The location of this member is important; to make sure contextDestroyed() notification on
     // ExecutionContext's members (notably m_timeouts) is called before they are destructed,
     // m_lifecycleNotifer should be placed *after* such members.