DevTools: use per-LocalFrame instrumenting agents instead of per-Page ones.

Source/core/frame/FrameHost.cpp

Index: Source/core/frame/FrameHost.cpp
diff --git a/Source/core/frame/FrameHost.cpp b/Source/core/frame/FrameHost.cpp
index 6bf82f3fe8be55e915bb97d9d9e251b1c82b7fb8..bcc05520a5a54b4fddfa488a3da01c7e96b76579 100644
--- a/Source/core/frame/FrameHost.cpp
+++ b/Source/core/frame/FrameHost.cpp
@@ -33,6 +33,7 @@
 
 #include "core/frame/EventHandlerRegistry.h"
 #include "core/inspector/ConsoleMessageStorage.h"
+#include "core/inspector/InspectorController.h"
 #include "core/page/Chrome.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/Page.h"
@@ -73,6 +74,11 @@ UseCounter& FrameHost::useCounter() const
     return m_page->useCounter();
 }
 
+InstrumentingAgents* FrameHost::instrumentingAgents() const
+{
+    return m_page->inspectorController().instrumentingAgents();
+}
+
 float FrameHost::deviceScaleFactor() const
 {
     return m_page->deviceScaleFactor();