Remove duplicate implementation of drawEllipse and some related PLATFORM(IOS) ifdefs

Remove duplicate implementation of drawEllipse and some related PLATFORM(IOS) ifdefs
https://bugs.webkit.org/show_bug.cgi?id=136413

Reviewed by Dan Bernstein.

No new tests, just cleanup.

* platform/graphics/GraphicsContext.cpp:
(WebCore::GraphicsContext::drawRaisedEllipse):
There's nothing iOS specific about this function.

* platform/graphics/GraphicsContext.h:
* platform/graphics/cairo/GraphicsContextCairo.cpp:
(WebCore::GraphicsContext::drawEllipse):
* platform/graphics/cg/GraphicsContextCG.cpp:
(WebCore::GraphicsContext::drawEllipse):
Un-ifdef drawRaisedEllipse; delete the reimplementation of drawEllipse that takes
a FloatRect and make the normal one take a FloatRect instead.

(WebCore::GraphicsContext::platformInit):
Make sure that the CGContext's line width starts out in sync with GraphicsContext's.
By default, CGContext has a line width of 1 and GraphicsContext 0, so they could previously
have been out of sync until someone set the width explicitly.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@173149 268f45cc-cd09-0410-ab3c-d52691b4dbfc