Change List constructors.

runtime/lib/string_base.dart

Index: runtime/lib/string_base.dart
diff --git a/runtime/lib/string_base.dart b/runtime/lib/string_base.dart
index b167e8027e5395da6244fca887100741092cfa81..db6f027b5ac6fc46227cd00aa4ce2357e42e44a9 100644
--- a/runtime/lib/string_base.dart
+++ b/runtime/lib/string_base.dart
@@ -248,7 +248,7 @@ class _StringBase {
    */
   static String _interpolate(List values) {
     int numValues = values.length;
-    var stringList = new List(numValues);
+    var stringList = new List.fixedLength(numValues);
     for (int i = 0; i < numValues; i++) {
       stringList[i] = values[i].toString();
     }
@@ -311,7 +311,7 @@ class _StringBase {
 
   List<String> splitChars() {
     int len = this.length;
-    final result = new List<String>(len);
+    final result = new List<String>.fixedLength(len);
     for (int i = 0; i < len; i++) {
       result[i] = this[i];
     }
@@ -320,7 +320,7 @@ class _StringBase {
 
   List<int> get charCodes {
     int len = this.length;
-    final result = new List<int>(len);
+    final result = new List<int>.fixedLength(len);
     for (int i = 0; i < len; i++) {
       result[i] = this.charCodeAt(i);
     }