Set the access qualifier of two methods to query frame specific info of BitmapImage to protected.
https://bugs.webkit.org/show_bug.cgi?id=90505

Patch by Huang Dongsung <luxtella@company100.net> on 2012-08-12
Reviewed by Eric Seidel.

Following 4 methods are protected.
  size_t frameCount();
  NativeImagePtr frameAtIndex(size_t);
  bool frameIsCompleteAtIndex(size_t);
  float frameDurationAtIndex(size_t);

So, 2 methds also should be protected because the frame info is only specific of
BitmapImage.
  bool frameHasAlphaAtIndex(size_t);
  ImageOrientation frameOrientationAtIndex(size_t);

On the other hand, this patch amended GraphicsContext3DCG.
- static_cast<BitmapImage*>(image)->frameHasAlphaAtIndex(0)
+ image->currentFrameHasAlpha()

This patch does not affect PNG, JPEG, BMP, and WEBP because those images
have only 0 indexed frame.
Thus, GIF, and ICO are affected. However, an above query to get Alpha
is for the image that is created by image->nativeImageForCurrentFrame(), so it
is proper to use image->currentFrameHasAlpha() instead of
image->frameHasAlphaAtIndex(0).

No new tests, because it is hard to test. We need an animated GIF that
one frame has alpha and another frame does not have alpha. However, I
cannot find the animated GIF file that suffices the requirement.

* platform/graphics/BitmapImage.h:
(BitmapImage):
* platform/graphics/cg/GraphicsContext3DCG.cpp:
(WebCore::GraphicsContext3D::getImageData):

git-svn-id: svn://svn.chromium.org/blink/trunk@125374 bbb929c8-8fbe-4397-9dbb-9b2b20218538