Don't crash if WebAXObject::characterOffsets doesn't return any bounds.

components/test_runner/web_ax_object_proxy.cc

 // Copyright 2014 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 "components/test_runner/web_ax_object_proxy.h"
 
 #include <stddef.h>
 
 #include "base/macros.h"
 #include "base/strings/stringprintf.h"
@@ skipping 339 matching lines @@
     blink::WebString name = inline_text_box.name();
     end += name.length();
     if (characterIndex < start || characterIndex >= end)
       continue;
 
     blink::WebFloatRect inline_text_box_rect = BoundsForObject(inline_text_box);
 
     int localIndex = characterIndex - start;
     blink::WebVector<int> character_offsets;
     inline_text_box.characterOffsets(character_offsets);
-    DCHECK(character_offsets.size() > 0 &&
-           character_offsets.size() == name.length());
+    if (character_offsets.size() != name.length())
+      return blink::WebRect();
+
     switch (inline_text_box.textDirection()) {
       case blink::WebAXTextDirectionLR: {
         if (localIndex) {
           int left = inline_text_box_rect.x + character_offsets[localIndex - 1];
           int width = character_offsets[localIndex] -
               character_offsets[localIndex - 1];
           return blink::WebRect(left, inline_text_box_rect.y,
                                 width, inline_text_box_rect.height);
         }
         return blink::WebRect(
@@ skipping 1328 matching lines @@
   v8::Local<v8::Value> value_handle = gin::CreateHandle(
       isolate, new WebAXObjectProxy(object, this)).ToV8();
   if (value_handle.IsEmpty())
     return v8::Local<v8::Object>();
   v8::Local<v8::Object> handle = value_handle->ToObject(isolate);
   elements_.Append(handle);
   return handle;
 }
 
 }  // namespace test_runner