[#229][Xooxle] Respond to keydown, not keyup.

This has the side effect that long presses result in the event being
registered repeatedly.

site/crum.ts

@@ -790,8 +790,8 @@ function main() {
 
   // NOTE: This is where we define all our command shortcuts. It's important for
   // the content to remain in sync with the help panel.
-  // TODO: (#280) Combine the help panel and `keyup` listener code.
-  document.addEventListener('keyup', (e: KeyboardEvent) => {
+  // TODO: (#280) Combine the help panel and `keydown` listener code.
+  document.addEventListener('keydown', (e: KeyboardEvent) => {
     if (e.metaKey || e.ctrlKey || e.altKey) {
       // If the user is holding down a modifier key, we don't want to do
       // anything.

site/xooxle.ts

@@ -537,9 +537,11 @@ function handleSearchQuery(timeout: number) {
 }
 
 searchBox.addEventListener('input', () => { handleSearchQuery(100); });
-// Prevent other elements in the page from picking up a `keyup` event on the
+// Prevent other elements in the page from picking up key events on the
 // search box.
 searchBox.addEventListener('keyup', (event: KeyboardEvent) => { event.stopPropagation(); });
+searchBox.addEventListener('keydown', (event: KeyboardEvent) => { event.stopPropagation(); });
+searchBox.addEventListener('keypress', (event: KeyboardEvent) => { event.stopPropagation(); });
 fullWordCheckbox.addEventListener('click', () => { handleSearchQuery(0); });
 regexCheckbox.addEventListener('click', () => { handleSearchQuery(0); });