Mark dart: libraries as not debuggable (by default)

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/become.h"
@@ skipping 10787 matching lines @@
       &result.raw_ptr()->patch_classes_,
       GrowableObjectArray::New(Object::empty_array(), Heap::kOld));
   result.StorePointer(&result.raw_ptr()->imports_, Object::empty_array().raw());
   result.StorePointer(&result.raw_ptr()->exports_, Object::empty_array().raw());
   result.StorePointer(&result.raw_ptr()->loaded_scripts_, Array::null());
   result.StorePointer(&result.raw_ptr()->load_error_, Instance::null());
   result.set_native_entry_resolver(NULL);
   result.set_native_entry_symbol_resolver(NULL);
   result.set_is_in_fullsnapshot(false);
   result.StoreNonPointer(&result.raw_ptr()->corelib_imported_, true);
-  result.set_debuggable(!dart_private_scheme);
+  if (dart_private_scheme) {
+    // Never debug dart:_ libraries.
+    result.set_debuggable(false);
+  } else if (dart_scheme) {
+    // Only debug dart: libraries if we have been requested to show invisible
+    // frames.
+    result.set_debuggable(FLAG_show_invisible_frames);
+  } else {
+    // Default to debuggable for all other libraries.
+    result.set_debuggable(true);
+  }
   result.set_is_dart_scheme(dart_scheme);
   result.StoreNonPointer(&result.raw_ptr()->load_state_,
                          RawLibrary::kAllocated);
   result.StoreNonPointer(&result.raw_ptr()->index_, -1);
   const intptr_t kInitialNameCacheSize = 64;
   result.InitResolvedNamesCache(kInitialNameCacheSize);
   result.InitClassDictionary();
   result.InitImportList();
   result.AllocatePrivateKey();
   if (import_core_lib) {
@@ skipping 12030 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart