Remove library tags, they aren't needed

lib/src/codegen/side_effect_analysis.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.
 
-library dev_compiler.src.codegen.side_effect_analysis;
-
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/constant.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/error.dart' show ErrorReporter;
 import 'package:analyzer/src/generated/engine.dart' show RecordingErrorListener;
 import 'package:analyzer/src/generated/resolver.dart' show TypeProvider;
 
 /// True is the expression can be evaluated multiple times without causing
 /// code execution. This is true for final fields. This can be true for local
 /// variables, if:
@@ skipping 105 matching lines @@
     // ConstantEvaluator will not compute constants for non-const fields,
     // so run ConstantVisitor for those to figure out if the initializer is
     // actually a constant (and therefore side effect free to evaluate).
     assert(!field.isConst);
 
     var initializer = field.initializer;
     if (initializer == null) return null;
     return initializer.accept(_constantVisitor);
   }
 }