Fix crash when the OfflineAudioContext constructor is given 0 as numberOfFrames

Source/modules/webaudio/OfflineAudioContext.cpp

 /*
  * Copyright (C) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 30 matching lines @@
     // FIXME: add support for workers.
     if (!context || !context->isDocument()) {
         es.throwDOMException(
             NotSupportedError,
             ExceptionMessages::failedToConstruct("OfflineAudioContext"));
         return 0;
     }
 
     Document* document = toDocument(context);
 
+    if (!numberOfFrames) {
+        es.throwDOMException(
+            SyntaxError,
+            ExceptionMessages::failedToConstruct(
+                "OfflineAudioContext",
+                "number of frames cannot be zero."));
+        return 0;
+    }
+
     if (numberOfChannels > 10) {
         es.throwDOMException(
             SyntaxError,
             ExceptionMessages::failedToConstruct(
                 "OfflineAudioContext",
                 "number of channels (" + String::number(numberOfChannels) + ") exceeds maximum (10)."));
         return 0;
     }
 
     if (!isSampleRateRangeGood(sampleRate)) {
@@ skipping 16 matching lines @@
     ScriptWrappable::init(this);
 }
 
 OfflineAudioContext::~OfflineAudioContext()
 {
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)