[Spellcheck] Don't initialize SpellcheckWordIterator with empty rulesets.

chrome/renderer/spellchecker/spellcheck_worditerator_unittest.cc

 // Copyright (c) 2012 The Chromium 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 <string>
 #include <vector>
 
 #include "base/format_macros.h"
 #include "base/stringprintf.h"
 #include "base/string_split.h"
@@ skipping 210 matching lines @@
 
     string16 actual_word;
     int actual_start, actual_end;
     EXPECT_TRUE(iterator.GetNextWord(&actual_word, &actual_start, &actual_end));
     if (kTestCases[i].left_to_right)
       EXPECT_EQ(input_word, actual_word);
     else
       EXPECT_NE(input_word, actual_word);
   }
 }
+
+TEST(SpellcheckWordIteratorTest, Initialization) {
+  // Test initialization works when a default language is set.
+  {
+    SpellcheckCharAttribute attributes;
+    attributes.SetDefaultLanguage("en-US");
+
+    SpellcheckWordIterator iterator;
+    EXPECT_TRUE(iterator.Initialize(&attributes, true));
+  }
+
+  // Test initialization fails when no default language is set.
+  {
+    SpellcheckCharAttribute attributes;
+
+    SpellcheckWordIterator iterator;
+    EXPECT_FALSE(iterator.Initialize(&attributes, true));
+  }
+}