Web Inspector: Native Memory Instrumentation: rename Image m_data member to m_encodedImageData for the consistency
https://bugs.webkit.org/show_bug.cgi?id=108913

Reviewed by Yury Semikhatsky.

No new tests because no API changes.

* platform/graphics/Image.cpp:
(WebCore::Image::setData):
(WebCore::Image::reportMemoryUsage):
* platform/graphics/Image.h:
(WebCore::Image::data):
(Image):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141874 268f45cc-cd09-0410-ab3c-d52691b4dbfc