Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/barback/lib/src/build_result.dart

+// Copyright (c) 2013, 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 barback.build_result;
+
+import 'errors.dart';
+import 'utils.dart';
+
+/// An event indicating that the cascade has finished building all assets.
+///
+/// A build can end either in success or failure. If there were no errors during
+/// the build, it's considered to be a success; any errors render it a failure,
+/// although individual assets may still have built successfully.
+class BuildResult {
+  // TODO(rnystrom): Revise how to track error results. Errors can come from
+  // both logs and exceptions. Accumulating them is likely slow and a waste of
+  // memory. If we do want to accumulate them, we should at least unify them
+  // in a single collection (probably of log entries).
+  /// All errors that were thrown during the build.
+  final Set<BarbackException> errors;
+
+  /// `true` if the build succeeded.
+  bool get succeeded => errors.isEmpty;
+
+  BuildResult(Iterable<BarbackException> errors)
+      : errors = flattenAggregateExceptions(errors).toSet();
+
+  /// Creates a build result indicating a successful build.
+  ///
+  /// This equivalent to a build result with no errors.
+  BuildResult.success()
+      : this([]);
+
+  /// Creates a single [BuildResult] that contains all of the errors of
+  /// [results].
+  factory BuildResult.aggregate(Iterable<BuildResult> results) {
+    var errors = unionAll(results.map((result) => result.errors));
+    return new BuildResult(errors);
+  }
+
+  String toString() {
+    if (succeeded) return "success";
+
+    return "errors:\n" + errors.map((error) {
+      var stackTrace = null;
+      if (error is TransformerException || error is AssetLoadException) {
+        stackTrace = error.stackTrace.terse;
+      }
+
+      var msg = new StringBuffer();
+      msg.write(prefixLines(error.toString()));
+      if (stackTrace != null) {
+        msg.write("\n\n");
+        msg.write("Stack chain:\n");
+        msg.write(prefixLines(stackTrace.toString()));
+      }
+      return msg.toString();
+    }).join("\n\n");
+  }
+}