Add 'dart:debugger' library

runtime/lib/debugger_sources.gypi

Index: runtime/lib/debugger_sources.gypi
diff --git a/runtime/lib/profiler_sources.gypi b/runtime/lib/debugger_sources.gypi
similarity index 73%
copy from runtime/lib/profiler_sources.gypi
copy to runtime/lib/debugger_sources.gypi
index 4d5ee05cfdd21df6f0b22b3d71cb82d33cf43ec3..3f54e81a0d5b0112ae67d6f0a86128a008bc3ac0 100644
--- a/runtime/lib/profiler_sources.gypi
+++ b/runtime/lib/debugger_sources.gypi
@@ -2,12 +2,12 @@
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
-# Sources visible via dart:profiler library.
+# Sources visible via dart:debugger library.
 
 {
   'sources': [
-    'profiler.cc',
-    'profiler.dart',
+    'debugger.cc',
+    'debugger.dart',
   ],
 }