Create our own blink_heap run_all_tests target to avoid piggy-backing on wtf's.

We used to use wtf's run_all_tests target to run out blink heap unittests. That causes a problem when we want to initialize our heap since we cannot call Heap::init/shutdown from wtf's RunAllTests since it cannot/should not depend on blink heap.

R=ager@chromium.org, erik.corry@gmail.com, haraken@chromium.org, vegorov@chromium.org, zerny@chromium.org
BUG=

Review URL: https://codereview.chromium.org/138133002

git-svn-id: svn://svn.chromium.org/blink/trunk@165073 bbb929c8-8fbe-4397-9dbb-9b2b20218538