Change new List(n) to return fixed length list.

tools/dom/templates/html/impl/impl_Document.darttemplate

Index: tools/dom/templates/html/impl/impl_Document.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_Document.darttemplate b/tools/dom/templates/html/impl/impl_Document.darttemplate
index ad71764c78516265a9776a75fa3b414c20160ce6..c1714b09cd946dee44a5107d48787f4d9e9a1713 100644
--- a/tools/dom/templates/html/impl/impl_Document.darttemplate
+++ b/tools/dom/templates/html/impl/impl_Document.darttemplate
@@ -61,7 +61,7 @@ $!MEMBERS
       final mutableMatches = $dom_getElementsByName(
           selectors.substring(7,selectors.length - 2));
       int len = mutableMatches.length;
-      final copyOfMatches = new List<Element>.fixedLength(len);
+      final copyOfMatches = new List<Element>(len);
       for (int i = 0; i < len; ++i) {
         copyOfMatches[i] = mutableMatches[i];
       }
@@ -69,7 +69,7 @@ $!MEMBERS
     } else if (new RegExp("^[*a-zA-Z0-9]+\$").hasMatch(selectors)) {
       final mutableMatches = $dom_getElementsByTagName(selectors);
       int len = mutableMatches.length;
-      final copyOfMatches = new List<Element>.fixedLength(len);
+      final copyOfMatches = new List<Element>(len);
       for (int i = 0; i < len; ++i) {
         copyOfMatches[i] = mutableMatches[i];
       }