Roll Observatory packages and add a roll script

packages/yaml/lib/src/scanner.dart

Index: packages/yaml/lib/src/scanner.dart
diff --git a/yaml/lib/src/scanner.dart b/packages/yaml/lib/src/scanner.dart
similarity index 99%
rename from yaml/lib/src/scanner.dart
rename to packages/yaml/lib/src/scanner.dart
index 2e02a8f7de8097b36fa0d261a4f0454b1ac37f1b..0ac86dce85e8b03747c273fa0993d310585785ee 100644
--- a/yaml/lib/src/scanner.dart
+++ b/packages/yaml/lib/src/scanner.dart
@@ -443,7 +443,8 @@ class Scanner {
           var token = _tokens.last;
           if (token.type == TokenType.FLOW_SEQUENCE_END ||
               token.type == TokenType.FLOW_MAPPING_END ||
-              (token.type == TokenType.SCALAR && token.style.isQuoted)) {
+              (token.type == TokenType.SCALAR &&
+                  (token as ScalarToken).style.isQuoted)) {
             _fetchValue();
             return;
           }