Introduce "platform configurations" to replace categories and libraries.dart.

tests/compiler/dart2js/platform_consistency_test.dart

+// Copyright (c) 2015, the Fletch 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.
+
+import "package:compiler/src/platform_configuration.dart";
+import "package:compiler/src/source_file_provider.dart";
+import "package:compiler/compiler_new.dart";
+import "package:expect/expect.dart";
+
+Uri unsupported =  Uri.parse("unsupported:");
+
+main() async {
+  CompilerInput input = new CompilerSourceFileProvider();
+  Map<String, Uri> client = await load(
+      Uri.base.resolve("sdk/lib/dart_client.platform"),
+      input);
+  Map<String, Uri> server = await load(
+      Uri.base.resolve("sdk/lib/dart_server.platform"),
+      input);
+  Map<String, Uri> shared = await load(
+      Uri.base.resolve("sdk/lib/dart_shared.platform"),
+      input);
+  Map<String, Uri> dart2dart = await load(
+      Uri.base.resolve("sdk/lib/dart2dart.platform"),
+      input);
+  Expect.setEquals(new Set.from(shared.keys), new Set.from(client.keys));
+  Expect.setEquals(new Set.from(shared.keys), new Set.from(server.keys));
+  Expect.setEquals(new Set.from(shared.keys), new Set.from(dart2dart.keys));
+
+  for (String libraryName in shared.keys) {
+    test(Map<String, Uri> m) {
+      if (m[libraryName] != unsupported &&
+          shared[libraryName] != unsupported) {
+        Expect.equals(shared[libraryName], m[libraryName]);
+      }
+    }
+    test(client);
+    test(server);
+    test(dart2dart);
+  }
+ }