Bug 1157984 - Part 3: Correct bounding box transformations to support projections and correct clipping when transforming behind the camera,r=vlad

- Update callsites of Matrix4x4::TransformBounds to use
  Matrix4x4::TransformAndClipBounds.

gfx/layers/basic/BasicLayerManager.cpp

@@ -761,14 +761,12 @@ Transform3D(RefPtr<SourceSurface> aSource,
             const Matrix4x4& aTransform,
             gfxRect& aDestRect)
 {
-  // Find the transformed rectangle of our layer.
-  gfxRect offsetRect = aBounds;
-  offsetRect.TransformBounds(aTransform);
-
-  // Intersect the transformed layer with the destination rectangle.
+  // Find the transformed rectangle of our layer, intersected with the
+  // destination rectangle.
   // This is in device space since we have an identity transform set on aTarget.
-  aDestRect = aDest->GetClipExtents();
-  aDestRect.IntersectRect(aDestRect, offsetRect);
+  aDestRect = ThebesRect(aTransform.TransformAndClipBounds(
+                ToRectDouble(aBounds),
+                ToRectDouble(aDest->GetClipExtents())));
   aDestRect.RoundOut();
 
   // Create a surface the size of the transformed object.