Add instance counters of Resource and AudioNode, and expose them via WebLeakDetector.

Source/core/fetch/Resource.h

Index: Source/core/fetch/Resource.h
diff --git a/Source/core/fetch/Resource.h b/Source/core/fetch/Resource.h
index 481cf6588e1e1da674308662dbae4a3bf4c3e240..157443890a34ee531010746355a4e7689b130fc3 100644
--- a/Source/core/fetch/Resource.h
+++ b/Source/core/fetch/Resource.h
@@ -93,6 +93,7 @@ public:
 #endif
     virtual void dispose();
     virtual void trace(Visitor*);
+    static unsigned instanceCount() { return s_instanceCount; }
 
     virtual void load(ResourceFetcher*, const ResourceLoaderOptions&);
 
@@ -401,6 +402,8 @@ private:
 
     // Ordered list of all redirects followed while fetching this resource.
     Vector<RedirectPair> m_redirectChain;
+
+    static unsigned s_instanceCount;
 };
 
 #if !LOG_DISABLED