Add "WTF_" prefix to  WTF "LOG" macro names in order to avoid "LOG" macro redefinition error

The "LOG" macro is defined in both Blink wtf/Assertions.h and in Chromium base/logging.h, this causes a compilation error in wtf/testing/RunAllTests.cpp file if the patch from https://codereview.chromium.org/88993002/ is applied.

Review URL: https://codereview.chromium.org/95303002

git-svn-id: svn://svn.chromium.org/blink/trunk@163001 bbb929c8-8fbe-4397-9dbb-9b2b20218538