https://bugs.webkit.org/show_bug.cgi?id=120791

Identical deviceScaleFactor calculations were performed in 3 different locations.
I've added that calculation as a method of Document.
Previous calculations are replaced by calls to this method.

Patch by Yoav Weiss <yoav@yoav.ws> on 2013-09-05
Reviewed by Andreas Kling.

No new tests since this is a refactoring change. No functionality have changed.

* dom/Document.cpp:
(WebCore::Document::deviceScaleFactor):
* dom/Document.h:
* html/HTMLImageElement.cpp:
(WebCore::HTMLImageElement::parseAttribute):
* html/parser/HTMLDocumentParser.cpp:
(WebCore::HTMLDocumentParser::pumpTokenizer):
(WebCore::HTMLDocumentParser::insert):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@155176 268f45cc-cd09-0410-ab3c-d52691b4dbfc