Infer transactional for anonymous functions

Part of #267.

lang/spec.html

@@ -5524,9 +5524,11 @@ <h3>Anonymous function expression</h3>
 </pre>
 <p>
 An infer-anonymous-function-expr can only be used in a context where a function
-type is expected. Both the types of the parameters and whether the function is
-isolated are inferred from the expected
-function type. The scope of the parameters is <code>expr-function-body</code>.
+type is expected. Both the types of the parameters and whether the function type
+is <code>isolated</code> are inferred from the expected function type. The
+function type will be inferred to be <code>transactional</code> if the
+expr-function-body calls any functions with a transactional type.
+The scope of the parameters is <code>expr-function-body</code>.
 The static type of the infer-anonymous-function-expr will be a function type
 whose return type is the static type of the <code>expression</code> in
 <code>expr-function-body</code>. If the contextually expected type for the