Fix Object.getOwnPropertyDescriptor in string elements.

This fixes Object.getOwnPropertyDescriptor to report string character
elements as enumerable in accordance with the spec.

BUG=v8:862
TEST=mjsunit/get-own-property-descriptor

Review URL: https://chromiumcodereview.appspot.com/9447053
Patch from Ioseb Dzmanashvili <ioseb.dzmanashvili@gmail.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10822 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/runtime.cc

@@ -1039,7 +1039,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_GetOwnProperty) {
         elms->set(IS_ACCESSOR_INDEX, heap->false_value());
         elms->set(VALUE_INDEX, *substr);
         elms->set(WRITABLE_INDEX, heap->false_value());
-        elms->set(ENUMERABLE_INDEX,  heap->false_value());
+        elms->set(ENUMERABLE_INDEX,  heap->true_value());
         elms->set(CONFIGURABLE_INDEX, heap->false_value());
         return *desc;
       }

test/mjsunit/get-own-property-descriptor.js

@@ -73,7 +73,7 @@ assertEquals(descObjectElement.value, 42);
 var a = new String('foobar');
 for (var i = 0; i < a.length; i++) {
   var descStringObject = Object.getOwnPropertyDescriptor(a, i);
-  assertFalse(descStringObject.enumerable);
+  assertTrue(descStringObject.enumerable);
   assertFalse(descStringObject.configurable);
   assertFalse(descStringObject.writable);
   assertEquals(descStringObject.value, a.substring(i, i+1));