fixing from generating huge imageframes with broken images. bug 76230. r=akkana, sr=hyatt

modules/libpr0n/src/imgContainer.cpp

@@ -32,7 +32,8 @@
 NS_IMPL_ISUPPORTS3(imgContainer, imgIContainer, nsITimerCallback,imgIDecoderObserver)
 
 //******************************************************************************
-imgContainer::imgContainer()
+imgContainer::imgContainer() :
+  mSize(0,0)
 {
   NS_INIT_ISUPPORTS();
   /* member initializers and constructor code */