Fix analyzer warnings in StringCanonicalizer

pkg/front_end/lib/src/fasta/scanner/canonicalizer.dart

Index: pkg/front_end/lib/src/fasta/scanner/canonicalizer.dart
diff --git a/pkg/front_end/lib/src/fasta/scanner/canonicalizer.dart b/pkg/front_end/lib/src/fasta/scanner/canonicalizer.dart
index 0848a081078eda53bbcf17b57020c4d12d48fea9..d5d76aa21666c62072f983399b9a8ba33b025b39 100644
--- a/pkg/front_end/lib/src/fasta/scanner/canonicalizer.dart
+++ b/pkg/front_end/lib/src/fasta/scanner/canonicalizer.dart
@@ -34,7 +34,7 @@ class StringCanonicalizer {
   /// Items in a hash table.
   int _count = 0;
   /// The table itself.
-  Node _nodes = new List<Node>(INITIAL_SIZE);
+  List<Node> _nodes = new List<Node>(INITIAL_SIZE);
 
   static String decode(List<int> data, int start, int end, bool asciiOnly) {
     var s;