WebKit should adopt journal_mode=wal for all SQLite databases.
<https://webkit.org/b/133496>
<rdar://problem/15600186>

We already had code to enable write-ahead logging, but it didn't work
since calling SQLiteStatement::step() without first calling prepare()
is a no-op.

Converted it to use into a simple executeCommand() instead.

Reviewed by Brady Eidson.

* platform/sql/SQLiteDatabase.cpp:
(WebCore::SQLiteDatabase::open):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@169587 268f45cc-cd09-0410-ab3c-d52691b4dbfc