fix(MdInput): invert password on-off icons (#2008)

Author: drhaliburton

src/components/MdField/MdField.vue

@@ -12,8 +12,8 @@
 
     <transition name="md-input-action" appear>
       <md-button tabindex="-1" class="md-icon-button md-dense md-input-action md-toggle-password" @click="togglePassword" v-if="hasPasswordToggle">
-        <md-password-off-icon v-if="MdField.togglePassword" />
-        <md-password-on-icon v-else />
+        <md-password-on-icon v-if="MdField.togglePassword" />
+        <md-password-off-icon v-else />
       </md-button>
     </transition>
   </div>
@@ -208,7 +208,6 @@
       font-family: inherit;
       font-size: 16px;
       line-height: $md-input-height;
-      box-shadow: 0px 0px transparent; // firefox required fix
 
       &[type="date"] {
         font-size: 16px;