Fix GC hazards associated with event handlers on images only reachable from their current network loads, some of which are regressions from 241518. b=321054 r=darin sr=bzbarsky

content/base/src/nsObjectLoadingContent.cpp

@@ -289,6 +289,7 @@ nsObjectLoadingContent::nsObjectLoadingContent()
 
 nsObjectLoadingContent::~nsObjectLoadingContent()
 {
+  DestroyImageLoadingContent();
   if (mFrameLoader) {
     mFrameLoader->Destroy();
   }