Add suppression for multipicturedraw_biglayer GM

TBR=reed@google.com
NOTRY=true

Review URL: https://codereview.chromium.org/631973002
diff --git a/expectations/gm/ignored-tests.txt b/expectations/gm/ignored-tests.txt
index 1308683..f489840 100644
--- a/expectations/gm/ignored-tests.txt
+++ b/expectations/gm/ignored-tests.txt
@@ -65,4 +65,7 @@
 xfermodes2
 xfermodes3
 
+# robertphillips - Fix multipicturedraw_biglayer GM - https://codereview.chromium.org/632743002
+multipicturedraw_biglayer_tiled
+multipicturedraw_biglayer_simple