Move all main methods to tool/.

pkg/front_end/lib/src/fasta/analyzer/compile_platform_dartk.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.
 
 library fasta.compile_platform;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show File, IOSink;
 
@@ skipping 42 matching lines @@
           null,
           null,
           "The environment variable '$name' has the value '$value', "
           "that's a directory that contains '$asyncSources', so it isn't a "
           "patched SDK. $what");
     }
     return null;
   }
 }
 
-main(List<String> arguments) async {
+mainEntryPoint(List<String> arguments) async {
   Uri output = Uri.base.resolveUri(new Uri.file(arguments.single));
   DartOptions options = new DartOptions(
       strongMode: false, sdk: await dartAotSdk.value, packagePath: null);
   Program program = new Program();
   DartLoader loader = new DartLoader(program, options, null,
       ignoreRedirectingFactories: false,
       dartSdk: createDartSdk(options.sdk, strongMode: options.strongMode));
   Target target =
       getTarget("vm", new TargetFlags(strongMode: options.strongMode));
   loader.loadProgram(Uri.base.resolve("pkg/fasta/test/platform.dart"),
@@ skipping 36 matching lines @@
           isConst: true,
           initializer: literal,
           fileUri: "${new Uri.file(source.fullName)}")..fileOffset = offset);
     }
   }
 
   IOSink sink = new File.fromUri(output).openWrite();
   new BinaryPrinter(sink).writeProgramFile(program);
   await sink.close();
 }