Allow Observatory debugger to switch isolates.

runtime/observatory/lib/src/cli/command.dart

Index: runtime/observatory/lib/src/cli/command.dart
diff --git a/runtime/observatory/lib/src/cli/command.dart b/runtime/observatory/lib/src/cli/command.dart
index 67b21c23504c8102a2b76161b944078d005f9d1d..9a338a36d924363e440e3198847d4297b47efcc9 100644
--- a/runtime/observatory/lib/src/cli/command.dart
+++ b/runtime/observatory/lib/src/cli/command.dart
@@ -149,11 +149,11 @@ class RootCommand extends _CommandBase {
     }
 
     // We have found a set of commands which match all of the args.
-    // Return the completions strings.
+    // Return the completion strings.
     var prefix = _concatArgs(args, args.length - 1);
     var completions =
         commands.map((command) => '${prefix}${command.name} ').toList();
-    if (showAll && matchLen == args.length) {
+    if (matchLen == args.length) {
       // If we are showing all possiblities, also include local
       // completions for the parent command.
       return commands[0]._parent._buildCompletions(args, false)