Make the terminal demo able (to try) to connect to anything.

sky/examples/terminal/index.sky

Index: sky/examples/terminal/index.sky
diff --git a/sky/examples/terminal/index.sky b/sky/examples/terminal/index.sky
index 74d56221b968981cbf8e486e993ac34e17a66422..2244afcedb1793d078bc59b8233d9718494f211d 100644
--- a/sky/examples/terminal/index.sky
+++ b/sky/examples/terminal/index.sky
@@ -5,4 +5,22 @@
 // found in the LICENSE file.
 -->
 <import src="terminal.sky" />
-<terminal url="mojo:echo_terminal" />
+<!--
+<terminal id="terminal" url="mojo:echo_terminal" />
+-->
+<terminal id="terminal" />
+<script>
+import 'dart:core';
+import 'dart:sky';
+
+main () {
+  var terminal = document.getElementById('terminal');
+  var params = Uri.parse(document.URL).queryParameters;
+  if (params.containsKey('url')) {
+    terminal.connect(params['url']);
+  } else {
+    terminal.putString('HALP: Add a "?url=<URL>" query.\n'
+                       'E.g., "?url=mojo:echo_terminal".\n');
+  }
+}
+</script>