how to select the dropdown using md-select and md-option in selenium webdriver.

Select class in not supported.

```html
<md-select placeholder="Filter" class="filter-select md-no-underline ng-pristine ng-valid ng-empty ng-touched" ng-model="$ctrl.dummy" aria-label="Filters" tabindex="0" aria-disabled="false" role="listbox" aria-expanded="false" aria-multiselectable="false" id="select_80" aria-invalid="false" style=""><md-select-value class="md-select-value md-select-placeholder" id="select_value_label_70"><span>Filter</span><span class="md-select-icon" aria-hidden="true"></span></md-select-value><div class="md-select-menu-container" aria-hidden="true" role="presentation" id="select_container_81"><md-select-menu role="presentation" class="_md"><md-content class="_md">
            <!-- ngRepeat: filter in $ctrl.allFilters --><md-option md-option-empty="" ng-repeat="filter in $ctrl.allFilters" ng-click="$ctrl.applyFilter(filter)" ng-keyup="$event.keyCode === 32 ? $ctrl.applyFilter(filter) : null" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_93"><div class="md-text ng-binding">
                Pending
            </div></md-option><!-- end ngRepeat: filter in $ctrl.allFilters --><md-option md-option-empty="" ng-repeat="filter in $ctrl.allFilters" ng-click="$ctrl.applyFilter(filter)" ng-keyup="$event.keyCode === 32 ? $ctrl.applyFilter(filter) : null" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_94"><div class="md-text ng-binding">
                Posted
            </div></md-option><!-- end ngRepeat: filter in $ctrl.allFilters --><md-option md-option-empty="" ng-repeat="filter in $ctrl.allFilters" ng-click="$ctrl.applyFilter(filter)" ng-keyup="$event.keyCode === 32 ? $ctrl.applyFilter(filter) : null" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_95"><div class="md-text ng-binding">
                Checks &amp; eChecks
            </div></md-option><!-- end ngRepeat: filter in $ctrl.allFilters --><md-option md-option-empty="" ng-repeat="filter in $ctrl.allFilters" ng-click="$ctrl.applyFilter(filter)" ng-keyup="$event.keyCode === 32 ? $ctrl.applyFilter(filter) : null" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_96"><div class="md-text ng-binding">
                Deposit
            </div></md-option><!-- end ngRepeat: filter in $ctrl.allFilters --><md-option md-option-empty="" ng-repeat="filter in $ctrl.allFilters" ng-click="$ctrl.applyFilter(filter)" ng-keyup="$event.keyCode === 32 ? $ctrl.applyFilter(filter) : null" tabindex="0" class="ng-scope md-ink-ripple" role="option" aria-selected="false" id="select_option_97"><div class="md-text ng-binding">
                Withdrawal
            </div></md-option><!-- end ngRepeat: filter in $ctrl.allFilters -->
        </md-content></md-select-menu></div></md-select>
```