[gtk] testsuite: Add a testcase for blend nodes with invisible children

[Timm Bäder <baedert src gnome org>]

commit 262ac4247ac420c6c1ed4f3169d5eb4c0a3efbfd
Author: Timm Bäder <mail baedert org>
Date:   Tue Jan 7 17:14:32 2020 +0100

    testsuite: Add a testcase for blend nodes with invisible children

 testsuite/gsk/compare/blend-invisible-child.node |  25 +++++++++++++++++++++++
 testsuite/gsk/compare/blend-invisible-child.png  | Bin 0 -> 221 bytes
 testsuite/gsk/meson.build                        |   1 +
 3 files changed, 26 insertions(+)
---
diff --git a/testsuite/gsk/compare/blend-invisible-child.node 
b/testsuite/gsk/compare/blend-invisible-child.node
new file mode 100644
index 0000000000..24981ca589
--- /dev/null
+++ b/testsuite/gsk/compare/blend-invisible-child.node
@@ -0,0 +1,25 @@
+blend {
+  top: color {
+    bounds: 0 0 50 50;
+    color: red;
+  }
+  bottom: color {
+    bounds: 25 25 0 10;
+    color: blue;
+  }
+  mode: multiply;
+}
+
+
+blend {
+  top: color {
+    bounds: 25 85 0 10;
+    color: blue;
+  }
+  bottom: color {
+    bounds: 0 60 50 50;
+    color: red;
+  }
+
+  mode: multiply;
+}
diff --git a/testsuite/gsk/compare/blend-invisible-child.png b/testsuite/gsk/compare/blend-invisible-child.png
new file mode 100644
index 0000000000..cbdb30c30d
Binary files /dev/null and b/testsuite/gsk/compare/blend-invisible-child.png differ
diff --git a/testsuite/gsk/meson.build b/testsuite/gsk/meson.build
index f82bfaef15..aadc40642b 100644
--- a/testsuite/gsk/meson.build
+++ b/testsuite/gsk/meson.build
@@ -63,6 +63,7 @@ compare_render_tests = [
   'repeat-negative-coords',
   'inset-shadow-multiple',
   'borders-rotated',
+  'blend-invisible-child',
 ]
 
 # these are too sensitive to differences in the renderers