Support a much larger subset of YAML.

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 ada81267d8c453120cd7f45035b72085b8656d54..d915294660833f15014156d230bf35400aeda73b 100644
--- a/utils/pub/yaml/composer.dart
+++ b/utils/pub/yaml/composer.dart
@@ -152,14 +152,18 @@ class _Composer extends _Visitor {
         "^[-+]?(\.[0-9]+|[0-9]+(\.[0-9]*)?)([eE][-+]?[0-9]+)?\$").
       firstMatch(content);
     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(@"\.$"), "");
       return new _ScalarNode(_Tag.yaml("float"),
-          value: Math.parseDouble(match.group(0)));
+          value: Math.parseDouble(matchStr));
     }
 
     match = const RegExp("^([+-]?)\.(inf|Inf|INF)\$").firstMatch(content);
     if (match != null) {
+      var infinityStr = match.group(1) == "-" ? "-Infinity" : "Infinity";
       return new _ScalarNode(_Tag.yaml("float"),
-          value: Math.parseDouble("${match.group(1)}Infinity"));
+          value: Math.parseDouble(infinityStr));
     }
 
     match = const RegExp("^\.(nan|NaN|NAN)\$").firstMatch(content);