Deprecate DirectoryBasedDartSdk and transition existing uses to the new API

pkg/analyzer/tool/summary/build_sdk_summaries.dart

 import 'dart:io';
 
-import 'package:analyzer/src/generated/sdk_io.dart';
+import 'package:analyzer/file_system/physical_file_system.dart';
+import 'package:analyzer/src/dart/sdk/sdk.dart';
 import 'package:analyzer/src/summary/flat_buffers.dart' as fb;
 import 'package:analyzer/src/summary/summary_file_builder.dart';
 
 main(List<String> args) {
   if (args.length < 1) {
     _printUsage();
     exitCode = 1;
     return;
   }
   String command = args[0];
@@ skipping 77 matching lines @@
   //
   // Validate the SDK path.
   //
   if (sdkPath != null) {
     if (!FileSystemEntity.isDirectorySync('$sdkPath/lib')) {
       print("'$sdkPath/lib' does not exist.");
       _printUsage();
       return null;
     }
   } else {
-    sdkPath = DirectoryBasedDartSdk.defaultSdkDirectory.getAbsolutePath();
+    sdkPath = FolderBasedDartSdk
+        .defaultSdkDirectory(PhysicalResourceProvider.INSTANCE)
+        .path;
   }
 
   //
   // Build spec and strong outputs.
   //
   BuilderOutput spec = includeSpec ? _buildOutput(sdkPath, false) : null;
   BuilderOutput strong = _buildOutput(sdkPath, true);
   return new SummaryOutput(spec, strong);
 }
 
@@ skipping 35 matching lines @@
   print('    Generate a single file with summary and index.');
   print('  extract-spec-sum input_file output_file');
   print('    Extract the spec-mode summary file.');
   print('  extract-strong-sum input_file output_file');
   print('    Extract the strong-mode summary file.');
   print('  extract-spec-index input_file output_file');
   print('    Extract the spec-mode index file.');
   print('  extract-strong-index input_file output_file');
   print('    Extract the strong-mode index file.');
 }