[librsvg: 13/13] Merge branch 'stacking-context' into 'master'

[Federico Mena Quintero <federico src gnome org>]

commit 8a150aadfc82694b62182f1d6f231a0e0dbae516
Merge: 5c1454a1 6bc3361e
Author: Federico Mena Quintero <federico mena gmail com>
Date:   Wed May 12 01:04:18 2021 +0000

    Merge branch 'stacking-context' into 'master'
    
    Use a StackingContext to do less work in DrawingCtx::with_discrete_layer
    
    See merge request GNOME/librsvg!521

 Makefile.am        |   1 +
 src/drawing_ctx.rs | 420 +++++++++++++++++++++++++++--------------------------
 src/element.rs     |   6 +-
 src/layout.rs      |  95 ++++++++++++
 src/lib.rs         |   1 +
 src/marker.rs      |  19 ++-
 src/structure.rs   |  79 +++++++---
 src/text.rs        |  62 ++++----
 8 files changed, 423 insertions(+), 260 deletions(-)
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