toString() on generator functions prints with function*

src/v8natives.js

Index: src/v8natives.js
diff --git a/src/v8natives.js b/src/v8natives.js
index 425863e5010fd63f3f9240b051e5007cca2450e7..9266af6f0c3243e063b9374fe0853a0b9e20c1d7 100644
--- a/src/v8natives.js
+++ b/src/v8natives.js
@@ -1665,7 +1665,6 @@ function FunctionSourceString(func) {
     func = %GetCallTrap(func);
   }
 
-  // TODO(wingo): Print source using function* for generators.
   if (!IS_FUNCTION(func)) {
     throw new $TypeError('Function.prototype.toString is not generic');
   }
@@ -1684,7 +1683,8 @@ function FunctionSourceString(func) {
   var name = %FunctionNameShouldPrintAsAnonymous(func)
       ? 'anonymous'
       : %FunctionGetName(func);
-  return 'function ' + name + source;
+  var head = %FunctionIsGenerator(func) ? 'function* ' : 'function ';
+  return head + name + source;
 }