[gtk/fix-calc-value-free] css: Fix freeing of calc values

[Matthias Clasen <matthiasc src gnome org>]

commit a52ee9ee22ed7b2ae564b5b9dc8cc31c16ceb336
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Aug 22 11:51:20 2022 -0400

    css: Fix freeing of calc values
    
    We were getting our memory allocations mixed
    up here.
    
    Fixes: #5130

 gtk/gtkcssnumbervalue.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkcssnumbervalue.c b/gtk/gtkcssnumbervalue.c
index 78e11b86ee..cd8c942c01 100644
--- a/gtk/gtkcssnumbervalue.c
+++ b/gtk/gtkcssnumbervalue.c
@@ -28,6 +28,7 @@
 static GtkCssValue *        gtk_css_calc_value_new         (guint n_terms);
 static GtkCssValue *        gtk_css_calc_value_new_sum     (GtkCssValue *a,
                                                             GtkCssValue *b);
+static gsize                gtk_css_value_calc_get_size    (gsize n_terms);
 
 enum {
   TYPE_CALC = 0,
@@ -78,9 +79,13 @@ gtk_css_value_number_free (GtkCssValue *number)
 
       for (guint i = 0; i < n_terms; i++)
         _gtk_css_value_unref (number->calc.terms[i]);
-    }
 
-  g_slice_free (GtkCssValue, number);
+      g_slice_free1 (gtk_css_value_calc_get_size (n_terms), number);
+    }
+  else
+    {
+      g_slice_free (GtkCssValue, number);
+    }
 }
 
 static double