Do not register Chromium's HTML5 DB VFS as the default

Do not register Chromium's HTML5 DB VFS as the default
VFS. Otherwise, other sqlite DB users in the same process will
stop working.

Reviewed by Dimitri Glazkov.

https://bugs.webkit.org/show_bug.cgi?id=31462

* platform/sql/chromium/SQLiteFileSystemChromium.cpp:
(WebCore::SQLiteFileSystem::openDatabase):
* platform/sql/chromium/SQLiteFileSystemChromiumPosix.cpp:
(WebCore::SQLiteFileSystem::registerSQLiteVFS):
* platform/sql/chromium/SQLiteFileSystemChromiumWin.cpp:
(WebCore::SQLiteFileSystem::registerSQLiteVFS):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@50954 268f45cc-cd09-0410-ab3c-d52691b4dbfc