added label to the timepicker button for screenreaders

src/locales/resources_en_US.json

@@ -863,6 +863,10 @@
     "_description": "Label for settings button in the tile",
     "message": "Settings"
   },
+  "timepicker_button_label": {
+    "_description": "Screen reader text for the timepicker component dropdown button",
+    "message": "Choose time"
+  },
   "timepicker_close": {
     "_description": "The close button for the timepicker modal",
     "message": "Done"

src/modules/timepicker/timepicker.component.html

@@ -2,8 +2,9 @@
   <ng-content></ng-content>
   <div class="sky-input-group-btn sky-input-group-timepicker-btn">
     <sky-dropdown
-      buttonType="clock-o"
       alignment="right"
+      buttonType="clock-o"
+      [label]="'timepicker_button_label' | skyResources"
       [messageStream]="dropdownController">
       <sky-dropdown-menu ariaRole="none">
         <sky-dropdown-item ariaRole="none">