Merge pull request #3233 from xixixao/issue2953cleanup

Clean up `Method calls on splice endpoints`

Author: vendethiel

lib/coffee-script/nodes.js

@@ -1274,9 +1274,9 @@ exports.Assign = class Assign extends Base
     else
       fromDecl = fromRef = '0'
     if to
-      if from and from instanceof Value and from?.isSimpleNumber() and
-                    to instanceof Value and to.isSimpleNumber()
-        to = +to.compile(o) - +fromRef
+      if from instanceof Value and from.isSimpleNumber() and
+         to instanceof Value and to.isSimpleNumber()
+        to = to.compile(o) - fromRef
         to += 1 unless exclusive
       else
         to = to.compile(o, LEVEL_ACCESS) + ' - ' + fromRef