Add --set-exit-code-on-problem option.

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 125 matching lines @@
 
   if (forVm) {
     // TODO(sigmund): add support for the flutter vmservice_sky as well.
     var vmserviceName = 'vmservice_io';
     var base = path.fromUri(Platform.script);
     Uri dartDir =
         new Uri.directory(path.dirname(path.dirname(path.absolute(base))));
     var program = await kernelForProgram(
         Uri.parse('dart:$vmserviceName'),
         new CompilerOptions()
+          ..setExitCodeOnProblem = true
           // TODO(sigmund): investigate. This should be outline, but it breaks
           // vm-debug tests. Issue #30111
           ..sdkSummary = platform
           ..dartLibraries = <String, Uri>{
             '_vmservice': dartDir.resolve('sdk/lib/vmservice/vmservice.dart'),
             'vmservice_io':
                 dartDir.resolve('runtime/bin/vmservice/vmservice_io.dart'),
           }
           ..packagesFileUri = packages);
     Uri vmserviceUri = outDirUri.resolve('$vmserviceName.dill');
@@ skipping 41 matching lines @@
 }
 
 /// Generates an outline.dill and platform.dill file containing the result of
 /// compiling a platform's SDK.
 ///
 /// Returns a list of dependencies read by the compiler. This list can be used
 /// to create GN dependency files.
 Future<List<Uri>> compilePlatform(Uri patchedSdk, Target target, Uri packages,
     Uri fullOutput, Uri outlineOutput) async {
   var options = new CompilerOptions()
+    ..setExitCodeOnProblem = true
     ..strongMode = false
     ..compileSdk = true
     ..sdkRoot = patchedSdk
     ..packagesFileUri = packages
     ..chaseDependencies = true
     ..target = target;
 
   var result = await generateKernel(
       new ProcessedOptions(
           options,
@@ skipping 522 matching lines @@
     if (diff != 0) return diff;
     return end - other.end;
   }
 }
 
 List<SdkLibrary> _getSdkLibraries(String contents) {
   var libraryBuilder = new SdkLibrariesReader_LibraryBuilder(forDart2js);
   parseCompilationUnit(contents).accept(libraryBuilder);
   return libraryBuilder.librariesMap.sdkLibraries;
 }