Go: Add stub expectsContent

Corresponds to #8870

Author: owen-mc

go/ql/lib/semmle/go/dataflow/internal/DataFlowPrivate.qll

@@ -188,6 +188,12 @@ predicate clearsContent(Node n, Content c) {
   // FlowSummaryImpl::Private::Steps::summaryClearsContent(n, c)
 }
 
+/**
+ * Holds if the value that is being tracked is expected to be stored inside content `c`
+ * at node `n`.
+ */
+predicate expectsContent(Node n, ContentSet c) { none() }
+
 /** Gets the type of `n` used for type pruning. */
 DataFlowType getNodeType(Node n) {
   result = n.getType()