Missing file from last commit.

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 9249 matching lines @@
 }
 
 
 RawString* String::SubString(const String& str,
                              intptr_t begin_index,
                              intptr_t length,
                              Heap::Space space) {
   ASSERT(!str.IsNull());
   ASSERT(begin_index >= 0);
   ASSERT(length >= 0);
-  if (begin_index >= str.Length()) {
+  if (begin_index <= str.Length() && length == 0) {
+    return Symbols::Empty();
+  }
+  if (begin_index > str.Length()) {
     return String::null();
   }
   String& result = String::Handle();
   bool is_one_byte_string = true;
   bool is_two_byte_string = true;
   intptr_t char_size = str.CharSize();
   if (char_size == kTwoByteChar) {
     for (intptr_t i = begin_index; i < begin_index + length; ++i) {
       if (str.CharAt(i) > 0xFF) {
         is_one_byte_string = false;
@@ skipping 1892 matching lines @@
   }
   return result.raw();
 }
 
 
 const char* WeakProperty::ToCString() const {
   return "_WeakProperty";
 }
 
 }  // namespace dart