[ast] Annotate some nodes with number of yields.

src/ast/ast-numbering.h

Index: src/ast/ast-numbering.h
diff --git a/src/ast/ast-numbering.h b/src/ast/ast-numbering.h
index 0ac1ef2134352ebe12d9b031b974ada2fd3ce598..9c178b4c517743a218a3b4524e98bb8c99ea6a2c 100644
--- a/src/ast/ast-numbering.h
+++ b/src/ast/ast-numbering.h
@@ -14,8 +14,9 @@ class Isolate;
 class Zone;
 
 namespace AstNumbering {
-// Assign type feedback IDs and bailout IDs to an AST node tree.
-//
+// Assign type feedback IDs and bailout IDs to an AST node tree.  For a
+// generator function, also annotate the function itself and any loops therein
+// with the number of contained yields.
 bool Renumber(Isolate* isolate, Zone* zone, FunctionLiteral* function);
 }