https://bugs.webkit.org/show_bug.cgi?id=91949

Reviewed by Adrienne Walker.

This is done by letting RenderScrollbarTheme::paintTickmarks()
delegate to the native ScrollbarTheme. To make this possible,
move paintTickmarks() from ScrollbarThemeComposite to the
superclass ScrollbarTheme.

For testing, add internals.addTextMatchMarker() and add a pixel test.

* platform/ScrollbarTheme.h:
(WebCore::ScrollbarTheme::paintTickmarks):
Moved paintTickmarks() from ScrollbarThemeComposite to here.
* platform/ScrollbarThemeComposite.h:
Remove paintTickmarks().
* platform/chromium/ScrollbarThemeChromium.cpp:
(WebCore::ScrollbarThemeChromium::paintTickmarks):
Switch to drawing tickmarks as vectors, so they can be arbitrarily wide.
* platform/chromium/ScrollbarThemeChromiumMac.h:
(ScrollbarThemeChromiumMac):
Implement paintTickmarks(), so that css-styled scrollbars get tickmarks on mac.
* platform/chromium/ScrollbarThemeChromiumMac.mm:
(WebCore::ScrollbarThemeChromiumMac::paint):
(WebCore::ScrollbarThemeChromiumMac::paintTickmarks):
Implement paintTickmarks(), so that css-styled scrollbars get tickmarks on mac.
* rendering/RenderScrollbarTheme.cpp:
(WebCore::RenderScrollbarTheme::paintTickmarks):
Delegate to the native ScrollbarTheme for tickmark drawing.
(WebCore):
* rendering/RenderScrollbarTheme.h:
(RenderScrollbarTheme):
Override paintTickmarks().


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@123418 268f45cc-cd09-0410-ab3c-d52691b4dbfc