QQuickBorderImage has no caching for .sci files.

In case you implement controls skinned using 9-sliced .png/.sci, all instances of given control
would parse the .sci file individually.
This has significant performance implications for scene setup times.
Relevant code path:
#5 0x0a554ffe in QFSFileEngine::open (this=0xa863b78, openMode=...)
at io/qfsfileengine.cpp:223
#6 0x0a51ee14 in QFile::open (this=0x7d4b0e4, mode=...) at
io/qfile.cpp:879
#7 0x78e38238 in QQuickBorderImage::load (this=0xa7f7120)
at items/qquickborderimage.cpp:311
#8 0x78e36a02 in QQuickImageBase::componentComplete (this=<optimized
out>)
at items/qquickimagebase.cpp:283

Note that the actual PNG is apparently perfectly cached in the asset atlas, just the .sci file
gets reparsed again and again for every instance.