Rewrite Error.prototype.toString in C++.

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 0adbc8fd1a3847630c1a9c804b2cced3be3898b1..4e7603de0541e8371063031d14585c7d276c7841 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -2744,6 +2744,15 @@ bool Genesis::InstallSpecialObjects(Handle<Context> native_context) {
                                 factory->stack_trace_symbol(), NONE),
                             false);
 
+  // Expose the internal error symbol to native JS
+  RETURN_ON_EXCEPTION_VALUE(isolate,
+                            JSObject::SetOwnPropertyIgnoreAttributes(
+                                handle(native_context->builtins(), isolate),
+                                factory->InternalizeOneByteString(
+                                    STATIC_CHAR_VECTOR("$internalErrorSymbol")),
+                                factory->internal_error_symbol(), NONE),
+                            false);
+
   // Expose the debug global object in global if a name for it is specified.
   if (FLAG_expose_debug_as != NULL && strlen(FLAG_expose_debug_as) != 0) {
     // If loading fails we just bail out without installing the