[minor] readTransaction allows modification in case of extra semicolon before SQL

[brodycj]

For example:

                  db.readTransaction(function (tx) {
                    tx.executeSql(';  CREATE TABLE TestTable (TestColumn)');
                  }, function(e) {
                    console.log('ERROR');
                  }, function() {
                    console.log('OK');
                  });

would be executed OK. Web SQL would call the error callback.