[runtime] Rewrite Function.prototype.toString in C++.

src/debug/mirrors.js

Index: src/debug/mirrors.js
diff --git a/src/debug/mirrors.js b/src/debug/mirrors.js
index b03f5125eb865bf031da4f93604abc772214a338..1fd5fa9ecd7222dca3026e5c48e848f3127d33b2 100644
--- a/src/debug/mirrors.js
+++ b/src/debug/mirrors.js
@@ -9,7 +9,6 @@
 // Imports
 
 var ErrorToString;
-var FunctionSourceString;
 var GlobalArray = global.Array;
 var IsNaN = global.isNaN;
 var JSONStringify = global.JSON.stringify;
@@ -25,7 +24,6 @@ var SymbolToString;
 
 utils.Import(function(from) {
   ErrorToString = from.ErrorToString;
-  FunctionSourceString = from.FunctionSourceString;
   MakeError = from.MakeError;
   MapEntries = from.MapEntries;
   MapIteratorNext = from.MapIteratorNext;
@@ -938,7 +936,7 @@ FunctionMirror.prototype.source = function() {
   // Return source if function is resolved. Otherwise just fall through to
   // return undefined.
   if (this.resolved()) {
-    return FunctionSourceString(this.value_);
+    return %FunctionToString(this.value_);

[Yang, 2015/12/22 06:19:22]

Alternatively, you could import global.Function.prototype.toString at the start
of this file and use it here. Then you don't have to introduce this %-function.

[Benedikt Meurer, 2015/12/22 06:30:35]

As per offline discussion: This doesn't work with the current bootstrapper
unfortunately because we need that in messages.js as well. So we'll keep it this
way instead for now.

   }
 };