cmd/cue/cmd: verify issue 236 is fixed

Closes #236

Change-Id: Idad78066be5987423cecf6f2319a17e8fda15bbf
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/7083
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: mpvl

cmd/cue/cmd/testdata/script/issue236.txt

@@ -0,0 +1,12 @@
+cue trim
+
+-- in.cue --
+package x
+
+#Schema: {
+    optional: string
+}
+d: #Schema
+d: {
+    optional: "some"
+}