Change restrictions on start/end on String.fromCharCodes.

runtime/lib/string_patch.dart

Index: runtime/lib/string_patch.dart
diff --git a/runtime/lib/string_patch.dart b/runtime/lib/string_patch.dart
index 76ad8ffd33ecf52499b3e99e3fda19fa19b98d88..d1bcc986aa395b9f01c5db56a124dfdb4fd085f7 100644
--- a/runtime/lib/string_patch.dart
+++ b/runtime/lib/string_patch.dart
@@ -57,7 +57,6 @@ class _StringBase {
   static String createFromCharCodes(Iterable<int> charCodes,
                                     int start, int end) {
     if (charCodes == null) throw new ArgumentError(charCodes);
-    if (start < 0) throw new RangeError.value(start);
     // TODO(srdjan): Also skip copying of wide typed arrays.
     final ccid = ClassID.getID(charCodes);
     bool isOneByteString = false;
@@ -70,10 +69,15 @@ class _StringBase {
         charCodes = new List.from(charCodes, growable: false);

[Søren Gjesse, 2014/09/26 11:43:00]

If the iterable is long (maybe even infinite) then this will create a long
list/go OOM even if only a small portion in the begining is requested.

Use skip/take pattern as in the dart2js code.

       }
     }
-    if ((end == null) || (end > charCodes.length)) {
-      end = charCodes.length;
+    int codeCount = charCodes.length;
+    if (start < 0 || start > codeCount) {
+      throw new RangeError.range(start, 0, codeCount);
+    }
+    if (end == null) {
+      end = codeCount;
+    } else if (end < start || end > codeCount) {
+      throw new RangeError.range(end, start, codeCount);
     }
-    if (end <= start) return "";
     final len = end - start;
     if (!isOneByteString) {
       for (int i = start; i < end; i++) {