[gtk+] gl: Fix copy&paste error in blur shader

[Timm Bäder <baedert src gnome org>]

commit cd2a53851b39fc1a97196aff031e6e6968abd885
Author: Timm Bäder <mail baedert org>
Date:   Mon Jan 8 18:36:48 2018 +0100

    gl: Fix copy&paste error in blur shader

 gsk/resources/glsl/blur.fs.glsl |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gsk/resources/glsl/blur.fs.glsl b/gsk/resources/glsl/blur.fs.glsl
index 8cf1e28..78107aa 100644
--- a/gsk/resources/glsl/blur.fs.glsl
+++ b/gsk/resources/glsl/blur.fs.glsl
@@ -18,7 +18,7 @@ vec4 blur_pixel (in vec2 uv) {
 
   for (int y = -half_radius; y < half_radius; y ++) {
     float fy = Gaussian (radius / 2.0, float(y));
-    float offset_y = y * pixel_size_x;
+    float offset_y = y * pixel_size_y;
 
     for (int x = -half_radius; x < half_radius; x ++) {
       float fx = Gaussian (radius / 2.0, float(x));