Always set the current NSGraphicsContext before calling drawWithFrame

Always set the current NSGraphicsContext before calling drawWithFrame
https://bugs.webkit.org/show_bug.cgi?id=42542

Reviewed by Dan Bernstein.

* rendering/RenderThemeMac.mm:
(WebCore::RenderThemeMac::paintMeter):
(WebCore::RenderThemeMac::paintSearchField):
(WebCore::RenderThemeMac::paintSearchFieldCancelButton):
(WebCore::RenderThemeMac::paintSearchFieldResultsDecoration):
(WebCore::RenderThemeMac::paintSearchFieldResultsButton):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@63642 268f45cc-cd09-0410-ab3c-d52691b4dbfc