[dartdevc] hide summarize-text option and change default to off

This option was useful early in development of DDC's Kernel backend, but
it shouldn't be turned on for users (we may want to remove it entirely).

Change-Id: Ie89115f6d3b9884762968e8e40bffa67799af988
Reviewed-on: https://dart-review.googlesource.com/c/93463
Auto-Submit: Jenny Messerly <jmesserly@google.com>
Reviewed-by: Vijay Menon <vsm@google.com>
Commit-Queue: Vijay Menon <vsm@google.com>
diff --git a/pkg/dev_compiler/lib/src/kernel/command.dart b/pkg/dev_compiler/lib/src/kernel/command.dart
index 15dd91c..e431f43 100644
--- a/pkg/dev_compiler/lib/src/kernel/command.dart
+++ b/pkg/dev_compiler/lib/src/kernel/command.dart
@@ -67,10 +67,11 @@
         abbr: 'h', help: 'Display this message.', negatable: false)
     ..addOption('out', abbr: 'o', help: 'Output file (required).')
     ..addOption('packages', help: 'The package spec file to use.')
-    // TODO(jmesserly): should default to `false` and be hidden.
-    // For now this is very helpful in debugging the compiler.
+    // TODO(jmesserly): is this still useful for us, or can we remove it now?
     ..addFlag('summarize-text',
-        help: 'emit API summary in a .js.txt file', defaultsTo: true)
+        help: 'emit API summary in a .js.txt file',
+        defaultsTo: false,
+        hide: true)
     // TODO(jmesserly): add verbose help to show hidden options
     ..addOption('dart-sdk-summary',
         help: 'The path to the Dart SDK summary file.', hide: true)