suppress matrixconvolution

BUG=skia:

Review URL: https://codereview.chromium.org/476283003

expectations/gm/ignored-tests.txt

diff --git a/expectations/gm/ignored-tests.txt b/expectations/gm/ignored-tests.txt
index df6af6e..d948cd4 100644
--- a/expectations/gm/ignored-tests.txt
+++ b/expectations/gm/ignored-tests.txt
@@ -44,3 +44,6 @@
 
 # To be rebaselined (fmalita)
 textblob
+
+# reed
+matrixconvolution