[builtins] implement Array.prototype[@@iterator] in TFJ builtins

src/ast/prettyprinter.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast/prettyprinter.h"
 
 #include <stdarg.h>
 
 #include "src/ast/ast-value-factory.h"
 #include "src/ast/scopes.h"
@@ skipping 511 matching lines @@
     } else if (object->IsJSArray()) {
       Print("JS-array[%u]",
             Smi::cast(JSArray::cast(object)->length())->value());
     } else if (object->IsJSObject()) {
       Print("JS-Object");
     } else {
       Print("?UNKNOWN?");
     }
   } else if (object->IsFixedArray()) {
     Print("FixedArray");
+  } else if (object->IsSymbol()) {
+    // Symbols can only occur as literals if they were inserted by the parser.
+    Symbol* symbol = Symbol::cast(object);
+    if (symbol->name()->IsString()) {
+      int length = 0;
+      String* string = String::cast(symbol->name());
+      std::unique_ptr<char[]> desc = string->ToCString(
+          ALLOW_NULLS, FAST_STRING_TRAVERSAL, 0, string->length(), &length);
+      Print("Symbol(%*s)", length, desc.get());
+    } else {
+      Print("Symbol()");
+    }
   } else {
     Print("<unknown literal %p>", static_cast<void*>(object));
   }
 }
 
 void AstPrinter::PrintLiteral(const AstRawString* value, bool quote) {
   PrintLiteral(value->string(), quote);
 }
 
 
@@ skipping 648 matching lines @@
 
 void AstPrinter::VisitRewritableExpression(RewritableExpression* node) {
   Visit(node->expression());
 }
 
 
 #endif  // DEBUG
 
 }  // namespace internal
 }  // namespace v8