Base: Add a browser test page that dumps out all mouse events

Base/res/html/misc/mouse-events.html

@@ -0,0 +1,22 @@
+<style>
+#rect {
+    width: 300px;
+    height: 300px;
+    border: 5px solid black;
+}
+</style>
+<div id=rect></div>
+<pre id=out></pre>
+<script>
+function handle(e) {
+    var out = document.getElementById('out');
+    out.innerHTML = e.type + ' @ ' + e.offsetX + ',' + e.y + '\n' + out.innerHTML;
+}
+
+var rect = document.getElementById('rect');
+rect.onmousedown = handle;
+rect.onmousemove = handle;
+rect.onmouseup = handle;
+rect.onclick = handle;
+rect.ondblclick = handle;
+</script>

Base/res/html/misc/welcome.html

@@ -135,6 +135,7 @@
 
         <h2>JavaScript/Wasm</h2>
         <ul>
+            <li><a href="mouse-events.html">mouse events</a></li>
             <li><a href="message-channel.html">MessageChannel</a></li>
             <li><a href="websocket.html">WebSocket API Test</a></li>
             <li><a href="cookie.html">document.cookie</a></li>