Add analysis options for front end, and fix a bug discovered by strong mode.

pkg/front_end/tool/perf.dart

 // Copyright (c) 2016, 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.
 
 /// An entrypoint used to run portions of front_end and measure its performance.
 library front_end.tool.perf;
 
 import 'dart:async';
 import 'dart:io' show exit, stderr;
 
@@ skipping 56 matching lines @@
       // the GC pressure on the VM seems to make this worse with time (maybe we
       // are leaking memory?). That's why we run it twice and not 10 times.
       for (int i = 0; i < 2; i++) await generateKernel(entryUri);
     },
   };
 
   var handler = handlers[bench];
   if (handler == null) {
     // TODO(sigmund): implement the remaining benchmarks.
     print('unsupported bench-id: $bench. Please specify one of the following: '
-        '${handler.keys.join(", ")}');
+        '${handlers.keys.join(", ")}');
     exit(1);
   }
   await handler();
 
   totalTimer.stop();
   report("total", totalTimer.elapsedMicroseconds);
 }
 
 /// Sets up analyzer to be able to load and resolve app, packages, and sdk
 /// sources.
@@ skipping 148 matching lines @@
     const int errorLimit = 100;
     stderr.writeln(errors.take(errorLimit).join('\n'));
     if (errors.length > errorLimit) {
       stderr.writeln('[error] ${errors.length - errorLimit} errors not shown');
     }
   }
   dartkTimer.stop();
   report("kernel_gen_e2e", dartkTimer.elapsedMicroseconds);
   return program;
 }