--- a/image/src/imgStatusTracker.cpp
+++ b/image/src/imgStatusTracker.cpp
@@ -295,17 +295,18 @@ private:
 
 // imgStatusTracker methods
 
 imgStatusTracker::imgStatusTracker(Image* aImage)
   : mImage(aImage),
     mState(0),
     mImageStatus(imgIRequest::STATUS_NONE),
     mIsMultipart(false),
-    mHadLastPart(false)
+    mHadLastPart(false),
+    mHasBeenDecoded(false)
 {
   mTrackerObserver = new imgStatusTrackerObserver(this);
 }
 
 // Private, used only by CloneForRecording.
 imgStatusTracker::imgStatusTracker(const imgStatusTracker& aOther)
   : mImage(aOther.mImage),
     mState(aOther.mState),
@@ -529,39 +530,49 @@ imgStatusTracker::CalculateAndApplyDiffe
   diff.mDiffState = ~mState & other->mState & ~stateRequestStarted;
   diff.mUnblockedOnload = mState & stateBlockingOnload && !(other->mState & stateBlockingOnload);
   diff.mFoundError = (mImageStatus != imgIRequest::STATUS_ERROR) && (other->mImageStatus == imgIRequest::STATUS_ERROR);
 
   // Now that we've calculated the difference in state, synchronize our state
   // with the other tracker.
 
   // First, actually synchronize our state.
-  diff.mInvalidRect = mInvalidRect.Union(other->mInvalidRect);
   mState |= diff.mDiffState | loadState;
   if (diff.mUnblockedOnload) {
     mState &= ~stateBlockingOnload;
   }
   mImageStatus = other->mImageStatus;
   mIsMultipart = other->mIsMultipart;
   mHadLastPart = other->mHadLastPart;
   mImageStatus |= other->mImageStatus;
+  mHasBeenDecoded = mHasBeenDecoded || other->mHasBeenDecoded;
 
   // The error state is sticky and overrides all other bits.
   if (mImageStatus & imgIRequest::STATUS_ERROR) {
     mImageStatus = imgIRequest::STATUS_ERROR;
   } else {
     // Unset the bits that can get unset as part of the decoding process.
     if (!(other->mImageStatus & imgIRequest::STATUS_DECODE_STARTED)) {
       mImageStatus &= ~imgIRequest::STATUS_DECODE_STARTED;
     }
   }
 
-  // Reset the invalid rectangles for another go.
-  other->mInvalidRect.SetEmpty();
-  mInvalidRect.SetEmpty();
+  // Only record partial invalidations if we haven't been decoded before.
+  // When images are re-decoded after discarding, we don't want to display
+  // partially decoded versions to the user.
+  bool doInvalidations  = !mHasBeenDecoded
+                       || mImageStatus & imgIRequest::STATUS_ERROR
+                       || mImageStatus & imgIRequest::STATUS_DECODE_COMPLETE;
+
+  // Record the invalid rectangles and reset them for another go.
+  if (doInvalidations) {
+    diff.mInvalidRect = mInvalidRect.Union(other->mInvalidRect);
+    other->mInvalidRect.SetEmpty();
+    mInvalidRect.SetEmpty();
+  }
 
   return diff;
 }
 
 void
 imgStatusTracker::SyncNotifyDifference(imgStatusTracker::StatusDiff diff)
 {
   LOG_SCOPE(GetImgLog(), "imgStatusTracker::SyncNotifyDifference");
@@ -763,16 +774,17 @@ imgStatusTracker::RecordStopDecode(nsres
 {
   NS_ABORT_IF_FALSE(mImage,
                     "RecordStopDecode called before we have an Image");
   mState |= stateDecodeStopped;
 
   if (NS_SUCCEEDED(aStatus) && mImageStatus != imgIRequest::STATUS_ERROR) {
     mImageStatus |= imgIRequest::STATUS_DECODE_COMPLETE;
     mImageStatus &= ~imgIRequest::STATUS_DECODE_STARTED;
+    mHasBeenDecoded = true;
   // If we weren't successful, clear all success status bits and set error.
   } else {
     mImageStatus = imgIRequest::STATUS_ERROR;
   }
 }
 
 void
 imgStatusTracker::SendStopDecode(imgRequestProxy* aProxy,

--- a/image/src/imgStatusTracker.h
+++ b/image/src/imgStatusTracker.h
@@ -241,11 +241,12 @@ private:
   nsTObserverArray<imgRequestProxy*> mConsumers;
 
   mozilla::RefPtr<imgDecoderObserver> mTrackerObserver;
 
   uint32_t mState;
   uint32_t mImageStatus;
   bool mIsMultipart    : 1;
   bool mHadLastPart    : 1;
+  bool mHasBeenDecoded : 1;
 };
 
 #endif