Correctly use sdk passed on command-line

pkg/analysis_server/lib/src/server/driver.dart

 // Copyright (c) 2014, 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 driver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 407 matching lines @@
       // No path to the SDK was provided.
       // Use DirectoryBasedDartSdk.defaultSdkDirectory, which will make a guess.
       defaultSdkPath = FolderBasedDartSdk
           .defaultSdkDirectory(PhysicalResourceProvider.INSTANCE)
           .path;
     }
     bool useSummaries = analysisServerOptions.fileReadMode == 'as-is';
     SdkCreator defaultSdkCreator = (AnalysisOptions options) {
       PhysicalResourceProvider resourceProvider =
           PhysicalResourceProvider.INSTANCE;
-      FolderBasedDartSdk sdk = new FolderBasedDartSdk(resourceProvider,
-          FolderBasedDartSdk.defaultSdkDirectory(resourceProvider));
+      FolderBasedDartSdk sdk = new FolderBasedDartSdk(
+          resourceProvider, resourceProvider.getFolder(defaultSdkPath));
       sdk.analysisOptions = options;
       sdk.useSummary = useSummaries;
       return sdk;
     };
     // TODO(brianwilkerson) It would be nice to avoid creating an SDK that
     // cannot be re-used, but the SDK is needed to create a package map provider
     // in the case where we need to run `pub` in order to get the package map.
     DartSdk defaultSdk = defaultSdkCreator(null);
     //
     // Initialize the instrumentation service.
@@ skipping 197 matching lines @@
    */
   static void _rollLogFiles(String path, int numOld) {
     for (int i = numOld - 1; i >= 0; i--) {
       try {
         String oldPath = i == 0 ? path : '$path.$i';
         new File(oldPath).renameSync('$path.${i+1}');
       } catch (e) {}
     }
   }
 }