Change links to buttons

- more semantically accurate, will expose these as buttons to assistive technologies
- note: while having block-level elements like `<div>` inside a `<button>` is an html validation error, it does not affect functionality as long as there's no more structure inside it

src/popup/accounts/login.component.html

@@ -28,11 +28,11 @@
                             class="monospaced" [(ngModel)]="masterPassword" required appInputVerbatim>
                     </div>
                     <div class="action-buttons">
-                        <a class="row-btn" href="#" appStopClick appBlurClick
+                        <button type="button" class="row-btn" appStopClick appBlurClick
                             appA11yTitle="{{'toggleVisibility' | i18n}}" (click)="togglePassword()">
                             <i class="fa fa-lg" [ngClass]="{'fa-eye': !showPassword, 'fa-eye-slash': showPassword}"
                                 aria-hidden="true"></i>
-                        </a>
+                        </button>
                     </div>
                 </div>
                 <div class="box-content-row" [hidden]="!showCaptcha()">