bug 1396836 - Tidy up about:telemetry search r=Dexter

Search would leave text in the input field when switching categories,
show a 'No search results' message on load, and show a 'No search results'
message in sections without search inputs.

Tidy those cases away.

MozReview-Commit-ID: BbkgIjq8fYD

--HG--
extra : rebase_source : 3d1b02d6c29096c42cdcce795689214b44b8cf00

toolkit/content/aboutTelemetry.js

@@ -1375,6 +1375,9 @@ var Search = {
       let sectionId = document.querySelector(".category.selected").getAttribute("value");
       section = document.getElementById(sectionId);
     }
+    if (Search.blacklist.includes(section.id)) {
+      return;
+    }
     let noSearchResults = true;
     if (section.id === "home-section") {
       return this.homeSearch(text);
@@ -1869,6 +1872,7 @@ function refreshSearch() {
 function adjustSearchState() {
   let selectedSection = document.querySelector(".category.selected").getAttribute("value");
   let search = document.getElementById("search");
+  search.value = "";
   search.hidden = Search.blacklist.includes(selectedSection);
   document.getElementById("no-search-results").classList.add("hidden");
   Search.search(""); // reinitialize search state.

toolkit/content/aboutTelemetry.xhtml

@@ -138,7 +138,7 @@
           <input type="text" id="search" placeholder=""/>
       </div>
 
-      <div id="no-search-results" hidden="true">
+      <div id="no-search-results" hidden="true" class="hidden">
         <span id="no-search-results-text"></span>
         <div class="no-search-results-image"></div>
       </div>