Text caret changes to color of text in Mail and Notes

Text caret changes to color of text in Mail and Notes
https://bugs.webkit.org/show_bug.cgi?id=135904

Patch by Myles C. Maxfield <mmaxfield@apple.com> on 2014-09-03
Reviewed by Simon Fraser.

Source/WebCore:

Consult with the background color of spans inside editable divs to determine what color
the caret should be.

Test: editing/caret/color-span-inside-editable.html

* editing/FrameSelection.cpp:
(WebCore::CaretBase::paintCaret):

LayoutTests:

Make sure the caret is the correct color.

* editing/caret/color-span-inside-editable-expected.html: Added.
* editing/caret/color-span-inside-editable.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@173246 268f45cc-cd09-0410-ab3c-d52691b4dbfc