Preload static strings into the AtomicStringTable

Static strings are immortal strings that are safe to use on any thread.
However, we can get confused on background threads that have AtomicStringTables
because the static strings are marked atomic but aren't in that thread's
AtomicStringTable.

In this CL, we preload the AtomicStringTable for every thread with all the
static strings. That means the static strings will be in every thread's atomic
string table, paving the way for removing thread-local event names.

R=dglazkov@chromium.org

Review URL: https://codereview.chromium.org/26009003

git-svn-id: svn://svn.chromium.org/blink/trunk@159072 bbb929c8-8fbe-4397-9dbb-9b2b20218538