Support directories other than "web" in pub build.

sdk/lib/_internal/pub/test/build/cleans_entire_build_directory_test.dart

Index: sdk/lib/_internal/pub/test/build/cleans_entire_build_directory_test.dart
diff --git a/sdk/lib/_internal/pub/test/build/cleans_entire_build_directory_test.dart b/sdk/lib/_internal/pub/test/build/cleans_entire_build_directory_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..142914aac7350865b018e953a8662c73dd81b0e8
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/build/cleans_entire_build_directory_test.dart
@@ -0,0 +1,39 @@
+// Copyright (c) 2014, 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.
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+
+main() {
+  initConfig();
+
+  integration("cleans entire build directory before a build", () {
+    d.dir(appPath, [
+      d.appPubspec(),
+      d.dir('example', [
+        d.file('file.txt', 'example')
+      ]),
+      d.dir('test', [
+        d.file('file.txt', 'test')
+      ])
+    ]).create();
+
+    // Make a build directory containing "example".
+    schedulePub(args: ["build", "example"],
+        output: new RegExp(r"Built 1 file!"));
+
+    // Now build again with just "test". Should wipe out "example".
+    schedulePub(args: ["build", "test"],
+        output: new RegExp(r"Built 1 file!"));
+
+    d.dir(appPath, [
+      d.dir('build', [
+        d.nothing('example'),
+        d.dir('test', [
+          d.file('file.txt', 'test')
+        ]),
+      ])
+    ]).validate();
+  });
+}