AccessibilityController::reset() should reset all notification listener callbacks.

Source/testing/runner/AccessibilityControllerChromium.cpp

Index: Source/testing/runner/AccessibilityControllerChromium.cpp
diff --git a/Source/testing/runner/AccessibilityControllerChromium.cpp b/Source/testing/runner/AccessibilityControllerChromium.cpp
index 3ea7fd682ac17e859e27c95b9faa3c63e84660fb..fbc0358d082f6764859ce208a5d519ecffaab094 100644
--- a/Source/testing/runner/AccessibilityControllerChromium.cpp
+++ b/Source/testing/runner/AccessibilityControllerChromium.cpp
@@ -69,6 +69,7 @@ void AccessibilityController::reset()
     m_rootElement = WebAccessibilityObject();
     m_focusedElement = WebAccessibilityObject();
     m_elements.clear();
+    m_notificationCallbacks.clear();
 
     m_logAccessibilityEvents = false;
 }