BitmapImage: Use the cheapest Vector constructor.

Source/platform/graphics/BitmapImage.cpp

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2008 Apple 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
@@ skipping 26 matching lines @@
 #include "wtf/CurrentTime.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
 BitmapImage::BitmapImage(ImageObserver* observer)
     : Image(observer)
     , m_currentFrame(0)
-    , m_frames(0)
+    , m_frames()

[jamesr, 2014/08/07 17:38:29]

why not just remove this line completely?

[Daniel Bratell, 2014/08/26 09:05:17]

It is a question of style, but in the work I've been doing performance have been
noticeably affected by code in Vector constructors and destructors so I felt it
was beneficial to list all the work done when the constructor runs. But it's a
question of style so I don't have any strong opinions.

     , m_frameTimer(0)
     , m_repetitionCount(cAnimationNone)
     , m_repetitionCountStatus(Unknown)
     , m_repetitionsComplete(0)
     , m_desiredFrameStartTime(0)
     , m_frameCount(0)
     , m_isSolidColor(false)
     , m_checkedForSolidColor(false)
     , m_animationFinished(false)
     , m_allDataReceived(false)
@@ skipping 566 matching lines @@
     }
     return m_isSolidColor && !m_currentFrame;
 }
 
 Color BitmapImage::solidColor() const
 {
     return m_solidColor;
 }
 
 }