Don't use regular expressions in Loader.

lib/src/yaml_node.dart

Index: lib/src/yaml_node.dart
diff --git a/lib/src/yaml_node.dart b/lib/src/yaml_node.dart
index 027bc1b32011ce2c85878fe6be7366e6962e60d7..d4961bb91d61bac5e8709acb6b9de6677e3e4215 100644
--- a/lib/src/yaml_node.dart
+++ b/lib/src/yaml_node.dart
@@ -9,6 +9,7 @@ import 'dart:collection' as collection;
 import 'package:collection/collection.dart';
 import 'package:source_span/source_span.dart';
 
+import 'event.dart';
 import 'null_span.dart';
 import 'style.dart';
 import 'yaml_node_wrapper.dart';
@@ -163,7 +164,14 @@ class YamlScalar extends YamlNode {
   }
 
   /// Users of the library should not use this constructor.
-  YamlScalar.internal(this.value, SourceSpan span, this.style) {
+  YamlScalar.internal(this.value, ScalarEvent scalar)
+      : style = scalar.style {
+    _span = span;
+  }
+
+  /// Users of the library should not use this constructor.
+  YamlScalar.internalWithSpan(this.value, SourceSpan span)
+      : style = ScalarStyle.ANY {
     _span = span;
   }