<md-content class="md-padding" ng-controller="TodoController as vm">
    <div layout="row">
        <h4 flex="82">{{vm.remaining()}} of {{vm.todos.length}} remaining</h4>
        <md-button class="md-primary" ng-click="vm.toggleAll()">Toggle All
        </md-button>
    </div>

    <md-checkbox ng-repeat="todo in vm.todos" ng-model="todo.done">
        {{todo.text}}
    </md-checkbox>

    <form ng-submit="vm.addTodo($event)" novalidate name="tasksForm">
        <div layout="row" flex>
            <md-input-container flex ng-class="{'md-input-invalid':tasksForm.taskText.$error.required && tasksForm.$submitted}">
                <label>Write some todo task here...</label>
                <input ng-model="vm.todoText" name="taskText" required>
            </md-input-container>
            <md-button class="md-fab md-wayrn md-mini">
                <i class="material-icons">add</i>
            </md-button>
        </div>
        <md-button class="md-primary" ng-click="vm.archive($event)">
            Remove completed
        </md-button>
    </form>
</md-content>
<md-content class="md-padding" ng-controller="TodoController as vm">
    <div layout="row">
        <h4 flex="82">{{vm.remaining()}} of {{vm.todos.length}} remaining</h4>
        <md-button class="md-primary" ng-click="vm.toggleAll()">Toggle All
        </md-button>
    </div>

    <md-checkbox ng-repeat="todo in vm.todos" ng-model="todo.done">
        {{todo.text}}
    </md-checkbox>

    <form ng-submit="vm.addTodo($event)" novalidate name="tasksForm">
        <div layout="row" flex>
            <md-input-container flex ng-class="{'md-input-invalid':tasksForm.taskText.$error.required && tasksForm.$submitted}">
                <label>Write some todo task here...</label>
                <input ng-model="vm.todoText" name="taskText" required>
            </md-input-container>
            <md-button class="md-fab md-wayrn md-mini" ng-click="vm.addTodo($event)">
                <i class="material-icons">add</i>
            </md-button>
        </div>
        <md-button class="md-primary" ng-click="vm.archive($event)">
            Remove completed
        </md-button>
    </form>
</md-content>

Add missing functionality to Add button
Add missing functionality to Add button

Current functionality, user had to hit enter to call the form submit and the plus button did nothing. Adds ng-click to element to allow for user to add items with the add button as well.