Normalize paths in PhysicalResourceProvider.getFile()/getFolder().

pkg/analyzer/lib/file_system/physical_file_system.dart

Index: pkg/analyzer/lib/file_system/physical_file_system.dart
diff --git a/pkg/analyzer/lib/file_system/physical_file_system.dart b/pkg/analyzer/lib/file_system/physical_file_system.dart
index 8b8618e2a16a68bd5420ca20ffb25467b9a956ff..b37fd72f7a9275e3a4bbc9643bcd25cac11dc86b 100644
--- a/pkg/analyzer/lib/file_system/physical_file_system.dart
+++ b/pkg/analyzer/lib/file_system/physical_file_system.dart
@@ -72,10 +72,16 @@ class PhysicalResourceProvider implements ResourceProvider {
   Context get pathContext => io.Platform.isWindows ? windows : posix;
 
   @override
-  File getFile(String path) => new _PhysicalFile(new io.File(path));
+  File getFile(String path) {
+    path = normalize(path);

[Brian Wilkerson, 2016/08/12 17:43:33]

Should this be "pathContext.normalize()"?

[scheglov, 2016/08/12 18:02:50]

It could be, but it does not have to.

We has "pathContext" mostly for the clients, to implement ResourceProvider.
Internally in the physical resource provider we know that "path" methods will
work as the physical file system needs.

+    return new _PhysicalFile(new io.File(path));
+  }
 
   @override
-  Folder getFolder(String path) => new _PhysicalFolder(new io.Directory(path));
+  Folder getFolder(String path) {
+    path = normalize(path);
+    return new _PhysicalFolder(new io.Directory(path));
+  }
 
   @override
   Future<List<int>> getModificationTimes(List<Source> sources) async {