Bug 1137058 - Increment RasterImage::mLockCount to ensure that non-discardable images don't eventually become unlocked. r=tn

image/src/RasterImage.cpp

@@ -326,6 +326,7 @@ RasterImage::Init(const char* aMimeType,
 
   // Lock this image's surfaces in the SurfaceCache if we're not discardable.
   if (!mDiscardable) {
+    mLockCount++;
     SurfaceCache::LockImage(ImageKey(this));
   }