Allow Directory.create to create all missing path components.

sdk/lib/_internal/dartdoc/lib/dartdoc.dart

Index: sdk/lib/_internal/dartdoc/lib/dartdoc.dart
diff --git a/sdk/lib/_internal/dartdoc/lib/dartdoc.dart b/sdk/lib/_internal/dartdoc/lib/dartdoc.dart
index a4a2a63d36f3eafc43640e6c9c0bce2a7aca26b6..41da802ec02d35816a39eed38de1bcec90f52871 100644
--- a/sdk/lib/_internal/dartdoc/lib/dartdoc.dart
+++ b/sdk/lib/_internal/dartdoc/lib/dartdoc.dart
@@ -75,7 +75,7 @@ Path get scriptDir =>
 void cleanOutputDirectory(Path path) {
   final outputDir = new Directory.fromPath(path);
   if (outputDir.existsSync()) {
-    outputDir.deleteRecursivelySync();
+    outputDir.deleteSync(recursive: true);
   }
 
   try {
@@ -564,7 +564,7 @@ class Dartdoc {
   void cleanup() {
     final dir = new Directory.fromPath(tmpPath);
     if (dir.existsSync()) {
-      dir.deleteRecursivelySync();
+      dir.deleteSync(recursive: true);
     }
   }