Big merge from experimental to bleeding edge.

pkg/path/lib/path.dart

Index: pkg/path/lib/path.dart
diff --git a/pkg/path/lib/path.dart b/pkg/path/lib/path.dart
index 99eee7be878563e637d2cd63fca651cdce0359aa..cc882f47f94ec460de01cea5264018b7ff8a941a 100644
--- a/pkg/path/lib/path.dart
+++ b/pkg/path/lib/path.dart
@@ -356,7 +356,7 @@ class Builder {
   List<String> split(String path) {
     var parsed = _parse(path);
     // Filter out empty parts that exist due to multiple separators in a row.
-    parsed.parts = parsed.parts.filter((part) => part != '');
+    parsed.parts = parsed.parts.where((part) => !part.isEmpty).toList();
     if (parsed.root != null) parsed.parts.insertRange(0, 1, parsed.root);
     return parsed.parts;
   }