Remove library tags, they aren't needed

lib/src/dart_sdk.dart

 // Copyright (c) 2015, 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.
 
 /// Common logic needed to provide a Dart SDK to the analyzer's resolver. This
 /// includes logic to determine where the sdk is located in the filesystem, and
 /// definitions to provide mock sdks.
-library dev_compiler.src.dart_sdk;
 
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, TimestampedData;
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/context/context.dart';
 
 /// Dart SDK which contains a mock implementation of the SDK libraries. May be
 /// used to speed up execution when most of the core libraries is not needed.
 class MockDartSdk implements DartSdk {
@@ skipping 155 matching lines @@
         ''',
   'dart:math': '''
         library dart.math;
         class Random {
           bool nextBool() {}
         }
         num min(num x, num y) {}
         num max(num x, num y) {}
         ''',
 };