fixing bug 78109 r=jband sr=brendan

modules/libpr0n/src/imgRequest.cpp

@@ -429,6 +429,9 @@ NS_IMETHODIMP imgRequest::OnStartContainer(imgIRequest *request, nsISupports *cx
 {
   LOG_SCOPE(gImgLog, "imgRequest::OnStartContainer");
 
+  NS_ASSERTION(image, "imgRequest::OnStartContainer called with a null image!");
+  if (!image) return NS_ERROR_UNEXPECTED;
+
   mState |= onStartContainer;
 
   mStatus |= imgIRequest::STATUS_SIZE_AVAILABLE;
@@ -629,7 +632,8 @@ NS_IMETHODIMP imgRequest::OnStopRequest(nsIRequest *aRequest, nsISupports *ctxt,
     mChannel = nsnull; // we no longer need the channel
   }
 
-  if (NS_FAILED(status)) {
+  // If mImage is still null, we didn't properly load the image.
+  if (NS_FAILED(status) || !mImage) {
     this->Cancel(status); // sets status, stops animations, removes from cache
   } else {
     mStatus |= imgIRequest::STATUS_LOAD_COMPLETE;

modules/libpr0n/src/imgRequest.h

@@ -56,11 +56,11 @@ class imgRequestProxy;
 }
 
 enum {
-  onStartDecode = 0x01,
+  onStartDecode    = PR_BIT(0),
-  onStartContainer = 0x02,
+  onStartContainer = PR_BIT(1),
-  onStopContainer = 0x04,
+  onStopContainer  = PR_BIT(2),
-  onStopDecode = 0x08,
+  onStopDecode     = PR_BIT(3),
-  onStopRequest = 0x16
+  onStopRequest    = PR_BIT(4)
 };
 
 class imgRequest : public imgIRequest,