Avoid object layout changes during GC.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 06a8458549104a088925775540e4a10e38d05c5a..c38ca8cb26ac6240b47e248b711312c33c57eec1 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -13109,19 +13109,38 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_MarkOneShotGetter) {
 }
 
 
-// Retrieve the raw stack trace collected on stack overflow and delete
-// it since it is used only once to avoid keeping it alive.
-RUNTIME_FUNCTION(MaybeObject*, Runtime_GetOverflowedRawStackTrace) {
+// Retrieve the stack trace.  This could be the raw stack trace collected
+// on stack overflow or the already formatted stack trace string.
+RUNTIME_FUNCTION(MaybeObject*, Runtime_GetOverflowedStackTrace) {
+  HandleScope scope(isolate);
   ASSERT_EQ(args.length(), 1);
   CONVERT_ARG_CHECKED(JSObject, error_object, 0);
   String* key = isolate->heap()->hidden_stack_trace_symbol();
   Object* result = error_object->GetHiddenProperty(key);
-  RUNTIME_ASSERT(result->IsJSArray() || result->IsUndefined());
-  error_object->DeleteHiddenProperty(key);
+  RUNTIME_ASSERT(result->IsJSArray() ||
+                 result->IsString() ||
+                 result->IsUndefined());
   return result;
 }
 
 
+// Set or clear the stack trace attached to an stack overflow error object.
+RUNTIME_FUNCTION(MaybeObject*, Runtime_SetOverflowedStackTrace) {
+  HandleScope scope(isolate);
+  ASSERT_EQ(args.length(), 2);
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, error_object, 0);
+  CONVERT_ARG_HANDLE_CHECKED(HeapObject, value, 1);
+  Handle<String> key = isolate->factory()->hidden_stack_trace_symbol();
+  if (value->IsUndefined()) {
+    error_object->DeleteHiddenProperty(*key);
+  } else {
+    RUNTIME_ASSERT(value->IsString());
+    JSObject::SetHiddenProperty(error_object, key, value);
+  }
+  return *error_object;
+}
+
+
 // Returns V8 version as a string.
 RUNTIME_FUNCTION(MaybeObject*, Runtime_GetV8Version) {
   ASSERT_EQ(args.length(), 0);