remove dependencies to analyzer from lib/src/fasta

pkg/front_end/lib/src/fasta/testing/patched_sdk_location.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.md file.
+
+/// Utility for locating the patched_sdk. This is temporarily used to run fasta
+/// until patching support is added.
+library fasta.testing.patched_sdk_location;
+
+import 'dart:async';
+import 'dart:io' show File, Platform;
+
+import 'environment_variable.dart' show EnvironmentVariable;
+
+Future<Uri> computePatchedSdk() async {
+  String config = await testConfigVariable.value;
+  String path;
+  switch (Platform.operatingSystem) {
+    case "linux":
+      path = "out/$config/patched_sdk";
+      break;
+
+    case "macos":
+      path = "xcodebuild/$config/patched_sdk";
+      break;
+
+    case "windows":
+      path = "build/$config/patched_sdk";
+      break;
+
+    default:
+      throw "Unsupported operating system: '${Platform.operatingSystem}'.";
+  }
+  Uri sdk = Uri.base.resolve("$path/");
+  const String asyncDart = "lib/async/async.dart";
+  if (!await fileExists(sdk, asyncDart)) {
+    throw "Couldn't find '$asyncDart' in '$sdk'.";
+  }
+  const String asyncSources = "lib/async/async_sources.gypi";
+  if (await fileExists(sdk, asyncSources)) {
+    throw "Found '$asyncSources' in '$sdk', so it isn't a patched SDK.";
+  }
+  return sdk;
+}
+
+Uri computeDartVm(Uri patchedSdk) {
+  return patchedSdk.resolve(Platform.isWindows ? "../dart.exe" : "../dart");
+}
+
+Future<bool> fileExists(Uri base, String path) async {
+  return await new File.fromUri(base.resolve(path)).exists();
+}
+
+final EnvironmentVariable testConfigVariable = new EnvironmentVariable(
+    "DART_CONFIGURATION",
+    "It should be something like 'ReleaseX64', depending on which"
+    " configuration you're testing.");