Add --analyze-signatures-only option to dart2js

sdk/lib/_internal/compiler/implementation/compiler.dart

 // Copyright (c) 2012, 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.
 
 part of dart2js;
 
 /**
  * If true, print a warning for each method that was resolved, but not
  * compiled.
  */
@@ skipping 198 matching lines @@
   final bool enableTypeAssertions;
   final bool enableUserAssertions;
   final bool enableConcreteTypeInference;
   /**
    * The maximum size of a concrete type before it widens to dynamic during
    * concrete type inference.
    */
   final int maxConcreteTypeSize;
   final bool analyzeAll;
   final bool analyzeOnly;
+  /**
+   * If true, skip analysis of method bodies and field initializers. Can only
+   * be used when [analyzeOnly] is set.
+   */
+  final bool analyzeSignaturesOnly;
   final bool enableNativeLiveTypeAnalysis;
   final bool rejectDeprecatedFeatures;
   final bool checkDeprecationInSdk;
 
   /**
    * If [:true:], comment tokens are collected in [commentMap] during scanning.
    */
   final bool preserveComments;
 
   final api.CompilerOutputProvider outputProvider;
@@ skipping 118 matching lines @@
             this.enableUserAssertions: false,
             this.enableConcreteTypeInference: false,
             this.maxConcreteTypeSize: 5,
             this.enableMinification: false,
             this.enableNativeLiveTypeAnalysis: false,
             bool emitJavaScript: true,
             bool generateSourceMap: true,
             bool disallowUnsafeEval: false,
             this.analyzeAll: false,
             this.analyzeOnly: false,
+            this.analyzeSignaturesOnly: false,
             this.rejectDeprecatedFeatures: false,
             this.checkDeprecationInSdk: false,
             this.preserveComments: false,
             outputProvider,
             List<String> strips: const []})
       : libraries = new Map<String, LibraryElement>(),
         progress = new Stopwatch(),
         this.outputProvider =
             (outputProvider == null) ? NullSink.outputProvider : outputProvider
   {
@@ skipping 791 matching lines @@
 
   void close() {}
 
   toString() => name;
 
   /// Convenience method for getting an [api.CompilerOutputProvider].
   static NullSink outputProvider(String name, String extension) {
     return new NullSink('$name.$extension');
   }
 }