Remove dead code in modules/webdatabase/.

This CL removes the follwings:

DatabaseBackendBase::details
DatabaseBackendBase::setAuthorizerReadOnly
DatabaseDetails class
DatabaseSync::backend
DatabaseSync::setLastErrorMessage(const char*, int)
DatabaseTracker::getOpenDatabases
SQLAuthIgnore
SQLError::create(unsigned, const char*, int)
SQLError::syntaxErrorMessage
SQLTransactionBackendSync::isReadOnly
SQLiteDatabase::clearAllTables
SQLiteDatabase::disableThreadingChecks
SQLiteDatabase::maximumSize
SQLiteDatabase::returnsAtLeastOneResult
SQLiteDatabase::setBusyHandler
SQLiteDatabase::setFullsync
SQLiteDatabase::setSynchronous
SQLiteFileSystem::appendDatabaseFileNameToPath
SQLiteFileSystem::deleteDatabaseFile
SQLiteFileSystem::deleteEmptyDatabaseDirectory
SQLiteFileSystem::ensureDatabaseDirectoryExists
SQLiteFileSystem::ensureDatabaseFileExists
SQLiteFileSystem::getDatabaseFileSize
SQLiteFileSystem::getFileNameForNewDatabase
SQLiteStatement::bindBlob(int const String&)
SQLiteStatement::bindBlob(int, const void*, int)
SQLiteStatement::bindInt
SQLiteStatement::bindInt64
SQLiteStatement::database
SQLiteStatement::getColumnBlob
SQLiteStatement::getColumnBlobAsString
SQLiteStatement::getColumnBlobAsVector
SQLiteStatement::isColumnDeclaredAsBlob
SQLiteStatement::isColumnNull
SQLiteStatement::isExpired
SQLiteStatement::query
SQLiteStatement::reset
SQLiteStatement::returnDoubleResults
SQLiteStatement::returnInt64Results
SQLiteStatement::returnIntResults
SQLiteStatement::returnsAtLeastOneResult

BUG=none
TEST=none; no behavior changes

Review URL: https://codereview.chromium.org/140353004

git-svn-id: svn://svn.chromium.org/blink/trunk@165206 bbb929c8-8fbe-4397-9dbb-9b2b20218538