Do not copy immutable arrays in String.createFromCharCodes. Tighten the types a little in string_pa…

runtime/lib/string_patch.dart

Index: runtime/lib/string_patch.dart
===================================================================
--- runtime/lib/string_patch.dart	(revision 22334)
+++ runtime/lib/string_patch.dart	(working copy)
@@ -27,9 +27,13 @@
    *  [codePoints].
    */
   static String createFromCharCodes(Iterable<int> charCodes) {
-    if (charCodes is! _ObjectArray && charCodes is! _GrowableObjectArray) {
+    // TODO(srdjan): Also skip copying of typed arrays.
+    if (charCodes is! _ObjectArray &&

[Ivan Posva, 2013/05/03 15:44:27]

This will not work long-term. Especially once we have "implements dynamic". What
we really need to do in the library implementations is have access to the
classId and check for those, as the VM implementation of the libraries is an
extension of the VM C++ code.

[srdjan, 2013/05/03 16:44:47]

Good point. What is the ETA for "implements dynamic". All "is" and "as" in VM
Dart libraries need to be checked and eventually replaced with a class-id check.

I will implement a direct class check and convert VM library code to use it.

+        charCodes is! _GrowableObjectArray &&
+        charCodes is! _ImmutableArray) {
       charCodes = new List<int>.from(charCodes, growable: false);
     }
+
     return _createFromCodePoints(charCodes);
   }
 
@@ -314,7 +318,7 @@
    */
   static String _interpolate(List values) {
     int numValues = values.length;
-    var stringList = new List(numValues);
+    _ObjectArray stringList = new List(numValues);
     for (int i = 0; i < numValues; i++) {
       stringList[i] = values[i].toString();
     }
@@ -428,7 +432,7 @@
     return _concatAll(stringsArray);
   }
 
-  static String _concatAll(List<String> strings)
+  static String _concatAll(_ObjectArray<String> strings)
       native "Strings_concatAll";
 }