Fix some grammatical errors in webkit/

webkit/plugins/npapi/plugin_instance.h

 // Copyright (c) 2011 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.
 
 // TODO: Need to deal with NPAPI's NPSavedData.
 //       I haven't seen plugins use it yet.
 
 #ifndef WEBKIT_PLUGINS_NPAPI_PLUGIN_INSTANCE_H_
 #define WEBKIT_PLUGINS_NPAPI_PLUGIN_INSTANCE_H_
 
@@ skipping 130 matching lines @@
   // list, which releases the reference maintained to the stream.
   void RemoveStream(PluginStream* stream);
 
   // Closes all open streams on this instance.
   void CloseStreams();
 
   // Returns the WebPluginResourceClient object for a stream that has become
   // seekable.
   WebPluginResourceClient* GetRangeRequest(int id);
 
-  // Have the plugin create it's script object.
+  // Have the plugin create its script object.
   NPObject* GetPluginScriptableObject();
 
   // Returns the form value of this instance.
   bool GetFormValue(string16* value);
 
   // WebViewDelegate methods that we implement. This is for handling
   // callbacks during getURLNotify.
   void DidFinishLoadWithReason(const GURL& url, NPReason reason, int notify_id);
 
   // If true, send the Mozilla user agent instead of Chrome's to the plugin.
@@ skipping 201 matching lines @@
  private:
   scoped_refptr<PluginInstance> instance_;
   DISALLOW_COPY_AND_ASSIGN(ScopedCurrentPluginEvent);
 };
 #endif
 
 }  // namespace npapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_NPAPI_PLUGIN_INSTANCE_H_