Bug 1177857 - Make job elements buttons instead of spans, for a11y

ui/css/treeherder.css

@@ -567,22 +567,23 @@ th-watched-repo {
     display: block;
 }
 
-.selected-job {
-    border: 4px solid;
-    background-color: #fff;
-}
-
 .job-group {
     margin: 0 -3px 0 3px;
 }
 
 .job-btn {
+  background: transparent;
   padding: 0 2px 0 2px;
   vertical-align: 0;
   line-height: 1.32;
   display: none;
 }
 
+.selected-job {
+    border: 4px solid;
+    background-color: #fff;
+}
+
 .filter-shown {
     display: inline-block;
 }

ui/index.html

@@ -179,10 +179,10 @@
 
         <!-- Job Btn span -->
         <script type="'text/ng-template'" id="jobBtnClone.html">
-            <span class="btn job-btn btn-xs {{ btnClass }} {{ key }}"
+            <button class="btn job-btn btn-xs {{ btnClass }} {{ key }}"
                   data-jmkey="{{ key }}"
                   ignore-job-clear-on-click
-                  title="{{ title }}">{{ value }}</span>
+                  title="{{ title }}">{{ value }}</button>
         </script>
 
         <!-- revision url window -->