Roll Observatory packages and add a roll script

packages/analyzer/lib/src/services/lint.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 lint;
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/visitors.dart';
 
+/// A registry containing mappings of contexts to their associated configured
+/// lints.
+final Map<AnalysisContext, List<Linter>> lintRegistry =
+    <AnalysisContext, List<Linter>>{};
+
 /// Implementers contribute lint warnings via the provided error [reporter].
 abstract class Linter {
   /// Used to report lint warnings.
   /// NOTE: this is set by the framework before visit begins.
   ErrorReporter reporter;
 
   /// Return a visitor to be passed to compilation units to perform lint
   /// analysis.
   /// Lint errors are reported via this [Linter]'s error [reporter].
   AstVisitor getVisitor();
 }
 
 /// Traverses a library's worth of dart code at a time to generate lint warnings
 /// over the set of sources.
 ///
 /// See [LintCode].
 class LintGenerator {
-
   /// A global container for contributed linters.
+  @deprecated // Use lintRegistry.
   static final List<Linter> LINTERS = <Linter>[];
 
   final Iterable<CompilationUnit> _compilationUnits;
   final AnalysisErrorListener _errorListener;
   final Iterable<Linter> _linters;
 
   LintGenerator(this._compilationUnits, this._errorListener,
       [Iterable<Linter> linters])
-      : _linters = linters != null ? linters : LINTERS;
+      : _linters = linters ?? LINTERS;
 
   void generate() {
     PerformanceStatistics.lint.makeCurrentWhile(() {
       _compilationUnits.forEach((cu) {
         if (cu.element != null) {
           _generate(cu, cu.element.source);
         }
       });
     });
   }
 
   void _generate(CompilationUnit unit, Source source) {
     ErrorReporter errorReporter = new ErrorReporter(_errorListener, source);
     _linters.forEach((l) => l.reporter = errorReporter);
     Iterable<AstVisitor> visitors = _linters.map((l) => l.getVisitor());
     unit.accept(new DelegatingAstVisitor(visitors.where((v) => v != null)));
   }
 }