Fix error with transforming custom/large glyphs

BUG=661244
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4738

Change-Id: I9f14ca830f9de92000e751a4a99ff1eb9b01db33
Reviewed-on: https://skia-review.googlesource.com/4866
Reviewed-by: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/gn/gm.gni b/gn/gm.gni
index 6a0b89f..0b11b2e 100644
--- a/gn/gm.gni
+++ b/gn/gm.gni
@@ -53,6 +53,7 @@
   "$_gm/circles.cpp",
   "$_gm/circulararcs.cpp",
   "$_gm/circularclips.cpp",
+  "$_gm/clip_error.cpp",
   "$_gm/clip_strokerect.cpp",
   "$_gm/clipdrawdraw.cpp",
   "$_gm/clippedbitmapshaders.cpp",