Convert raw strings in pub (and apidoc) to new syntax.

utils/pub/yaml/composer.dart

Index: utils/pub/yaml/composer.dart
diff --git a/utils/pub/yaml/composer.dart b/utils/pub/yaml/composer.dart
index 18df4e8f451e06ad04f1a0c163d38a095dc6c491..52d9885097d46a7770ae6060de9cd48ef5217be2 100644
--- a/utils/pub/yaml/composer.dart
+++ b/utils/pub/yaml/composer.dart
@@ -154,7 +154,7 @@ class _Composer extends _Visitor {
     if (match != null) {
       // YAML allows floats of the form "0.", but Dart does not. Fix up those
       // floats by removing the trailing dot.
-      var matchStr = match.group(0).replaceAll(new RegExp(@"\.$"), "");
+      var matchStr = match.group(0).replaceAll(new RegExp(r"\.$"), "");
       return new _ScalarNode(_Tag.yaml("float"),
           value: Math.parseDouble(matchStr));
     }