Restore partial analysis of analysis options files

pkg/analyzer_cli/lib/src/analyzer_impl.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 analyzer_cli.src.analyzer_impl;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:io';
 
@@ skipping 151 matching lines @@
 
   Future<ErrorSeverity> _analyze(
       int printMode, ErrorFormatter formatter) async {
     // Don't try to analyze parts.
     String path = librarySource.fullName;
     SourceKind librarySourceKind = analysisDriver != null
         ? await analysisDriver.getSourceKind(path)
         : context.computeKindOf(librarySource);
     if (librarySourceKind == SourceKind.PART) {
       stderr.writeln("Only libraries can be analyzed.");
-      stderr.writeln("${path} is a part and can not be analyzed.");
+      stderr.writeln("$path is a part and can not be analyzed.");
       return ErrorSeverity.ERROR;
     }
 
     LibraryElement libraryElement = await _resolveLibrary();
     prepareSources(libraryElement);
     await prepareErrors();
 
     // Print errors and performance numbers.
     if (printMode == 1) {
       formatter.formatErrors(errorInfos);
@@ skipping 120 matching lines @@
   }
 
   @override
   void logInformation(String message, [CaughtException exception]) {
     outSink.writeln(message);
     if (exception != null) {
       outSink.writeln(exception);
     }
   }
 }