Adding test case for interaction between record subtyping and record extension

testsuite/compiler/compute/Records.gf

@@ -0,0 +1,12 @@
+resource Records = {
+
+param P = A;
+
+oper
+  hello = id "hello";
+  -- Id should be an identity function for Str
+--id : Str -> Str = \ s -> s ;
+  id : Str -> Str = \ s -> ({a=s}**f r).a;
+  f : { b:Str } -> { b:Str } = \ x -> x;
+  r : { a:P; b:Str} = {a=A;b="b"};
+}

testsuite/compiler/compute/Records.gfs

@@ -0,0 +1,2 @@
+i -retain testsuite/compiler/compute/Records.gf
+cc hello

testsuite/compiler/compute/Records.gfs.gold

@@ -0,0 +1 @@
+"hello"