Add blank default to copy container selector

Author: aaronkollasch

src/ui/options.html

@@ -95,6 +95,7 @@ <h3 class="flextabs__tab"><button class="flextabs__toggle enforcement_required">
   <div class="per-site-buttons" id="per-site-buttons">
     <label for="copy-container" id="copy-container-label">Copy permissions from container:</label>
     <select name="copy-container" id="copy-container">
+      <option value=blank></option>
       <option value="default">Default</option>
     </select>
     <div style="inline-size:0;margin-inline:.5em;border:1px solid #888"></div>

src/ui/options.js

@@ -231,6 +231,7 @@ document.querySelector("#version").textContent = _("Version",
       sitesUI.policy = currentPolicy;
       sitesUI.render(currentPolicy.sites);
     }
+    containerCopy.value = "blank";
   }
   containerCopy.onchange = copyContainer;
 
@@ -251,7 +252,7 @@ document.querySelector("#version").textContent = _("Version",
     }
     containerSelect.innerHTML = container_options;
     containerSelect.value = cookieStoreId;
-    containerCopy.innerHTML = container_options;
+    containerCopy.innerHTML = "<option value=blank></option>" + container_options;
   }
   containerSelect.onfocus = updateContainerOptions;
   containerCopy.onfocus = updateContainerOptions;