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

chrome/renderer/spellchecker/spellcheck_worditerator.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.
 
 // Implements a custom word iterator used for our spellchecker.
 
 #include "chrome/renderer/spellchecker/spellcheck_worditerator.h"
 
 #include <map>
 #include <string>
@@ skipping 294 matching lines @@
 
 bool SpellcheckWordIterator::Initialize(
     const SpellcheckCharAttribute* attribute,
     bool allow_contraction) {
   // Create a custom ICU break iterator with empty text used in this object. (We
   // allow setting text later so we can re-use this iterator.)
   DCHECK(attribute);
   UErrorCode open_status = U_ZERO_ERROR;
   UParseError parse_status;
   string16 rule(attribute->GetRuleSet(allow_contraction));
+
+  // If there is no rule set, the attributes were invalid.
+  if (rule.empty())
+    return false;
+
   iterator_ = ubrk_openRules(rule.c_str(), rule.length(), NULL, 0,
                              &parse_status, &open_status);
   if (U_FAILURE(open_status))
     return false;
 
   // Set the character attributes so we can normalize the words extracted by
   // this iterator.
   attribute_ = attribute;
   return true;
 }
@@ skipping 86 matching lines @@
   if (status != U_ZERO_ERROR && status != U_STRING_NOT_TERMINATED_WARNING)
     return false;
 
   // Copy the normalized text to the output.
   icu::StringCharacterIterator it(output);
   for (UChar c = it.first(); c != icu::CharacterIterator::DONE; c = it.next())
     attribute_->OutputChar(c, output_string);
 
   return !output_string->empty();
 }