Ensure VCL instance actions imply method calls

bin/varnishtest/tests/v00018.vtc

@@ -147,3 +147,11 @@ varnish v1 -errvcl {Syntax error} {
 		directors.round_robin.backend();
 	}
 }
+
+varnish v1 -errvcl {Expected '.' got ';'} {
+	import directors;
+	sub vcl_init {
+		new rr = directors.round_robin();
+		rr;
+	}
+}

lib/libvcc/vcc_expr.c

@@ -1431,6 +1431,7 @@ vcc_Act_Obj(struct vcc *tl, struct token *t, struct symbol *sym)
 	struct expr *e = NULL;
 
 	assert(sym->kind == SYM_INSTANCE);
+	ExpectErr(tl, '.');
 	tl->t = t;
 	vcc_expr4(tl, &e, sym->type);
 	ERRCHK(tl);