[EFL] Enable WebP support.
https://bugs.webkit.org/show_bug.cgi?id=136156

Patch by KwangHyuk Kim <hyuki.kim@samsung.com> on 2014-10-11
Reviewed by Gyuyoung Kim.

.:

Add WebP package finding rule.

* Source/cmake/OptionsEfl.cmake:

Source/WebCore:

Add WebP library and inlcude path to WebCore path for WK2 Efl.
No new tests since existing feature is just enabled for WK2 Efl.

* PlatformEfl.cmake:

Source/WTF:

Enable WTF_USE_WEBP macro for WK2 Efl.

* wtf/Platform.h:

Tools:

Include libwebp-dev package to support WebP for WK2 Efl.

* efl/install-dependencies:

LayoutTests:

Clarify skipped webp test for Webkit EFL.

* platform/efl/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@174633 268f45cc-cd09-0410-ab3c-d52691b4dbfc
After r174628 we send the test process a SIGTERM before the SIGKILL.

* Scripts/webkitpy/common/system/executive_unittest.py:
(ExecutiveTest.serial_test_kill_process):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@174634 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Mark some more tests as sometimes passing.

* platform/mac-wk2/TestExpectations:
* platform/mac/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@174635 268f45cc-cd09-0410-ab3c-d52691b4dbfc