Add observatory_pub_packages snapshot to third_party

observatory_pub_packages/source_maps/source_maps.dart

Index: observatory_pub_packages/source_maps/source_maps.dart
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--- observatory_pub_packages/source_maps/source_maps.dart	(revision 0)
+++ observatory_pub_packages/source_maps/source_maps.dart	(working copy)
@@ -0,0 +1,44 @@
+// 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 to create and parse source maps.
+///
+/// Create a source map using [SourceMapBuilder]. For example:
+///     var json = (new SourceMapBuilder()
+///         ..add(inputSpan1, outputSpan1)
+///         ..add(inputSpan2, outputSpan2)
+///         ..add(inputSpan3, outputSpan3)
+///         .toJson(outputFile);
+///
+/// Use the source_span package's [SourceSpan] and [SourceFile] classes to
+/// specify span locations.
+///
+/// Parse a source map using [parse], and call `spanFor` on the returned mapping
+/// object. For example:
+///     var mapping = parse(json);
+///     mapping.spanFor(outputSpan1.line, outputSpan1.column)
+///
+/// ## Getting the code ##
+///
+/// This library is distributed as a [pub][] package. To install this package,
+/// add the following to your `pubspec.yaml` file:
+///
+///     dependencies:
+///       source_maps: any
+///
+/// After you run `pub install`, you should be able to access this library by
+/// importing `package:source_maps/source_maps.dart`.
+///
+/// For more information, see the
+/// [source_maps package on pub.dartlang.org][pkg].
+///
+/// [pub]: http://pub.dartlang.org
+/// [pkg]: http://pub.dartlang.org/packages/source_maps
+library source_maps;
+
+export "builder.dart";
+export "parser.dart";
+export "printer.dart";
+export "refactor.dart";
+export 'src/source_map_span.dart';