[babl] babl: in babl_polynomial_approximate_gamma(), verify that x0 >= 0

[N/A <ell src gnome org>]

commit 1434937088f68ce24eb4b3008108019243d3a2bc
Author: Ell <ell_se yahoo com>
Date:   Sun Sep 24 17:46:50 2017 -0400

    babl: in babl_polynomial_approximate_gamma(), verify that x0 >= 0
    
    Now that the previous commit (hopefully) makes us iPhone-proof, we
    can add an assertion for this condition.  If we want to replace the
    assertions with some sort of bailing, we'll need to replace the rest
    of them too anyway.

 babl/babl-polynomial.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/babl/babl-polynomial.c b/babl/babl-polynomial.c
index c9f195b..82f9ce4 100644
--- a/babl/babl-polynomial.c
+++ b/babl/babl-polynomial.c
@@ -516,6 +516,7 @@ babl_polynomial_approximate_gamma (BablPolynomial *poly,
 
   babl_assert (poly != NULL);
   babl_assert (gamma >= 0.0);
+  babl_assert (x0 >= 0.0);
   babl_assert (x0 < x1);
   babl_assert (degree >= BABL_POLYNOMIAL_MIN_DEGREE &&
                degree <= BABL_POLYNOMIAL_MAX_DEGREE);