Bug 538310, clean up old mimetype code, r=jst, sr=sicking

dom/base/nsMimeTypeArray.h

@@ -102,6 +102,8 @@ public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIDOMMIMETYPE
 
+  void DetachPlugin() { mPlugin = nsnull; }
+
 protected:
   nsIDOMPlugin* mPlugin;
   nsCOMPtr<nsIDOMMimeType> mMimeType;

dom/base/nsPluginArray.cpp

@@ -285,8 +285,13 @@ nsPluginElement::~nsPluginElement()
   NS_IF_RELEASE(mPlugin);
 
   if (mMimeTypeArray != nsnull) {
-    for (PRUint32 i = 0; i < mMimeTypeCount; i++)
-      NS_IF_RELEASE(mMimeTypeArray[i]);
+    for (PRUint32 i = 0; i < mMimeTypeCount; i++) {
+      nsMimeType* mt = static_cast<nsMimeType*>(mMimeTypeArray[i]);
+      if (mt) {
+        mt->DetachPlugin();
+        NS_RELEASE(mt);
+      }
+    }
     delete[] mMimeTypeArray;
   }
 }