Fix more tests on windows bots

pkg/analyzer/lib/src/dart/sdk/sdk.dart

 // Copyright (c) 2016, 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.src.generated.sdk2;
 
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:io' as io;
 
@@ skipping 663 matching lines @@
     return sdkDirectory;
   }
 
   static String getSdkProperty(ResourceProvider resourceProvider) {
     String exec = io.Platform.resolvedExecutable;
     if (exec.length == 0) {
       return null;
     }
     pathos.Context pathContext = resourceProvider.pathContext;
     if (pathContext.style != pathos.context.style) {
-      // This will only be true if pathContext == posix and
-      // pathos.context == windows, which only happens when running tests.
+      // This will only happen when running tests.
       if (exec.startsWith(new RegExp('[a-zA-Z]:'))) {
         exec = exec.substring(2);
+      } else if (resourceProvider is MemoryResourceProvider) {
+        exec = resourceProvider.convertPath(exec);
       }
       exec = pathContext.fromUri(pathos.context.toUri(exec));
     }
     // Might be "xcodebuild/ReleaseIA32/dart" with "sdk" sibling
     String outDir = pathContext.dirname(pathContext.dirname(exec));
     String sdkPath = pathContext.join(pathContext.dirname(outDir), "sdk");
     if (resourceProvider.getFolder(sdkPath).exists) {
       return sdkPath;
     }
     // probably be "dart-sdk/bin/dart"
@@ skipping 179 matching lines @@
     SdkLibrariesReader_LibraryBuilder libraryBuilder =
         new SdkLibrariesReader_LibraryBuilder(_useDart2jsPaths);
     // If any syntactic errors were found then don't try to visit the AST
     // structure.
     if (!errorListener.errorReported) {
       unit.accept(libraryBuilder);
     }
     return libraryBuilder.librariesMap;
   }
 }