Silence a compiler warning about initialization order of RasterImage members, no bug

--HG--
extra : rebase_source : a109b2d20f362add2dbb38a6b2037adfab69941e

image/src/RasterImage.cpp

@@ -235,8 +235,8 @@ RasterImage::RasterImage(imgStatusTracker* aStatusTracker) :
   mInDecoder(false),
   mAnimationFinished(false),
   mFinishing(false),
-  mScaleRequest(this),
-  mInUpdateImageContainer(false)
+  mInUpdateImageContainer(false),
+  mScaleRequest(this)
 {
   // Set up the discard tracker node.
   mDiscardTrackerNode.img = this;