[gtk+] Avoid super-luminous pixels

[Matthias Clasen <matthiasc src gnome org>]

commit b564dd853c52c3a2e3e1fd35a4f951cb128c0641
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Oct 19 15:15:13 2017 +0200

    Avoid super-luminous pixels
    
    The color-matrix shader was creating pixels with r,g,b > a in
    some cases, which leads to unexpected test failures. In particular
    this as visible the opacity render node test for opacity 0.

 .../vulkan/color-matrix-clip-rounded.frag.spv      |  Bin 9676 -> 9568 bytes
 gsk/resources/vulkan/color-matrix-clip.frag.spv    |  Bin 2824 -> 2716 bytes
 gsk/resources/vulkan/color-matrix.frag             |    3 +--
 gsk/resources/vulkan/color-matrix.frag.spv         |  Bin 2824 -> 2716 bytes
 4 files changed, 1 insertions(+), 2 deletions(-)
---
diff --git a/gsk/resources/vulkan/color-matrix-clip-rounded.frag.spv 
b/gsk/resources/vulkan/color-matrix-clip-rounded.frag.spv
index 2025e85..d25714e 100644
Binary files a/gsk/resources/vulkan/color-matrix-clip-rounded.frag.spv and 
b/gsk/resources/vulkan/color-matrix-clip-rounded.frag.spv differ
diff --git a/gsk/resources/vulkan/color-matrix-clip.frag.spv b/gsk/resources/vulkan/color-matrix-clip.frag.spv
index ec29f26..a9bd797 100644
Binary files a/gsk/resources/vulkan/color-matrix-clip.frag.spv and 
b/gsk/resources/vulkan/color-matrix-clip.frag.spv differ
diff --git a/gsk/resources/vulkan/color-matrix.frag b/gsk/resources/vulkan/color-matrix.frag
index 00b7947..8787eb4 100644
--- a/gsk/resources/vulkan/color-matrix.frag
+++ b/gsk/resources/vulkan/color-matrix.frag
@@ -22,8 +22,7 @@ color_matrix (vec4 color, mat4 color_matrix, vec4 color_offset)
   color = clamp(color, 0.0, 1.0);
 
   /* premultiply */
-  if (color.a != 0.0)
-    color.rgb *= color.a;
+  color.rgb *= color.a;
 
   return color;
 }
diff --git a/gsk/resources/vulkan/color-matrix.frag.spv b/gsk/resources/vulkan/color-matrix.frag.spv
index ec29f26..a9bd797 100644
Binary files a/gsk/resources/vulkan/color-matrix.frag.spv and b/gsk/resources/vulkan/color-matrix.frag.spv 
differ