Revert "Fix for #22"

This reverts commit 955761f46fcec73c91c5dbf2547b6f88afb5d3fc.

Bug: https://github.com/flutter/flutter/issues/110673
Change-Id: Ie076e9740cf66523f788197047bd378a41b46f2c
Reviewed-on: https://flutter-review.googlesource.com/c/third_party/libtess2/+/35005
Reviewed-by: Zach Anderson <zra@google.com>
Commit-Queue: Jonah Williams <jonahwilliams@google.com>

Source/sweep.c

diff --git a/Source/sweep.c b/Source/sweep.c
index 32a56bf..5fc1d97 100755
--- a/Source/sweep.c
+++ b/Source/sweep.c
@@ -493,7 +493,7 @@
 			SpliceMergeVertices( tess, eLo->Oprev, eUp );
 		}
 	} else {
-		if( EdgeSign( eUp->Dst, eLo->Org, eUp->Org ) <= 0 ) return FALSE;
+		if( EdgeSign( eUp->Dst, eLo->Org, eUp->Org ) < 0 ) return FALSE;
 
 		/* eLo->Org appears to be above eUp, so splice eLo->Org into eUp */
 		RegionAbove(regUp)->dirty = regUp->dirty = TRUE;