Revert "Add support for building patched_sdk and platform.dill for dart2js:"

pkg/compiler/tool/generate_kernel.dart

-// Copyright (c) 2017, 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.
-
-/// Helper to run fasta with the right target configuration to build dart2js
-/// applications using the dart2js platform libraries.
-// TODO(sigmund): delete this file once we can configure fasta directly on the
-// command line.
-library compiler.tool.generate_kernel;
-
-import 'dart:io' show exitCode;
-
-import 'package:front_end/src/fasta/compiler_command_line.dart'
-    show CompilerCommandLine;
-import 'package:front_end/src/fasta/compiler_context.dart' show CompilerContext;
-import 'package:front_end/src/fasta/errors.dart' show InputError;
-import 'package:front_end/src/fasta/ticker.dart' show Ticker;
-import 'package:compiler/src/kernel/fasta_support.dart' show Dart2jsCompileTask;
-
-main(List<String> arguments) async {
-  try {
-    await CompilerCommandLine.withGlobalOptions("generate_kernel", arguments,
-        (CompilerContext c) async {
-      if (c.options.verbose) {
-        print("Compiling directly to Kernel: ${arguments.join(' ')}");
-      }
-      var task =
-          new Dart2jsCompileTask(c, new Ticker(isVerbose: c.options.verbose));
-      await task.compile();
-    });
-  } on InputError catch (e) {
-    exitCode = 1;
-    print(e.format());
-    return null;
-  }
-}