Allow the VM to read Kernel files with external libraries

tools/patch_sdk.dart

 #!/usr/bin/env dart
 // Copyright (c) 2015, 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.
 
 /// Command line tool to merge the SDK libraries and our patch files.
 /// This is currently designed as an offline tool, but we could automate it.
 
 import 'dart:io';
 import 'dart:isolate' show RawReceivePort;
@@ skipping 146 matching lines @@
           },
         }
       }
     });
     Uri vmserviceJsonUri = outDirUri.resolve("lib/vmservice_libraries.json");
     await _writeSync(vmserviceJsonUri.toFilePath(), vmserviceJson);
     var program = await kernelForProgram(
         Uri.parse('dart:$vmserviceName'),
         new CompilerOptions()
           ..setExitCodeOnProblem = true
-          // TODO(sigmund): investigate. This should be outline, but it breaks
-          // vm-debug tests. Issue #30111
-          ..sdkSummary = platform
+          ..sdkSummary = outline
           ..librariesSpecificationUri = vmserviceJsonUri
           ..packagesFileUri = packages);
     Uri vmserviceUri = outDirUri.resolve('$vmserviceName.dill');
-    // TODO(sigmund): remove. This is a workaround because in the VM
-    // doesn't support loading vmservice if it contains external libraries
-    // (there is an assertion that only fails in debug builds). Issue #30111
-    program.libraries.forEach((l) => l.isExternal = false);
     await writeProgramToFile(program, vmserviceUri);
   }
 
   Uri platformFinalLocation = outDirUri.resolve('platform.dill');
 
   // We generate a dependency file for GN to properly regenerate the patched sdk
   // folder, outline.dill and platform.dill files when necessary: either when
   // the sdk sources change or when this script is updated. In particular:
   //
   //  - sdk changes: we track the actual sources we are compiling. If we are
@@ skipping 634 matching lines @@
   var libraryBuilder = new SdkLibrariesReader_LibraryBuilder(forDart2js);
   parseCompilationUnit(contents).accept(libraryBuilder);
   return libraryBuilder.librariesMap.sdkLibraries;
 }
 
 void addLocation(Map<String, Map<String, String>> locations, String libraryName,
     String libraryPath) {
   assert(locations[libraryName] == null);
   locations[libraryName] = {'uri': '${path.toUri(libraryPath)}'};
 }