Properly parse library names on Windows in pub.

utils/pub/validator/name.dart

Index: utils/pub/validator/name.dart
diff --git a/utils/pub/validator/name.dart b/utils/pub/validator/name.dart
index 3a37e31dd9f10e14e9f064893608e539d84e5e65..570f8b8302bce638dfe2f83b8ffbffb2a39fe525 100644
--- a/utils/pub/validator/name.dart
+++ b/utils/pub/validator/name.dart
@@ -33,7 +33,7 @@ class NameValidator extends Validator {
       for (var file in files) {
         if (file.contains("/src/")) continue;
         if (new Path(file).extension != 'dart') continue;
-        var libName = new Path(file).filenameWithoutExtension;
+        var libName = new Path(basename(file)).filenameWithoutExtension;
         _checkName(libName, 'The name of "$file", "$libName",');
       }
     });