Inspector: replace generic discardAgents logic with explicit call to discard a listener.

Source/core/inspector/InspectorController.cpp

Index: Source/core/inspector/InspectorController.cpp
diff --git a/Source/core/inspector/InspectorController.cpp b/Source/core/inspector/InspectorController.cpp
index ec60e0c9b12ca499fe1e6c6e5b9103ccd9e9f2f6..8ffeeb16e388ee3675cb645bc87db7880cf317ba 100644
--- a/Source/core/inspector/InspectorController.cpp
+++ b/Source/core/inspector/InspectorController.cpp
@@ -168,7 +168,6 @@ InspectorController::InspectorController(Page* page, InspectorClient* inspectorC
 InspectorController::~InspectorController()
 {
     m_instrumentingAgents->reset();
-    m_agents.discardAgents();
     ASSERT(!m_inspectorClient);
 }