Change restrictions on start/end on String.fromCharCodes.

runtime/lib/string_patch.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 patch class String {
   /* patch */ factory String.fromCharCodes(Iterable<int> charCodes,
                                            [int start = 0, int end]) {
     return _StringBase.createFromCharCodes(charCodes, start, end);
   }
 
@@ skipping 39 matching lines @@
 
   int get hashCode native "String_getHashCode";
 
   /**
    *  Create the most efficient string representation for specified
    *  [codePoints].
    */
   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;
     if ((ccid != ClassID.cidArray) &&
         (ccid != ClassID.cidGrowableObjectArray) &&
         (ccid != ClassID.cidImmutableArray)) {
-      if ((charCodes is Uint8List) || (charCodes is Int8List)) {
+      if (charCodes is Uint8List) {
         isOneByteString = true;
       } else {
-        charCodes = new List.from(charCodes, growable: false);
+        // Treat charCodes as Iterable.
+        if (start < 0) throw new RangeError.range(start, 0, charCodes.length);
+        if (end != null && end < start) {
+          throw new RangeError.value(end, start, charCodes.length);
+        }
+        var it = charCodes.iterator;
+        for (int i = 0; i < start; i++) {
+          if (!it.moveNext()) {
+            throw new RangeError.range(start, 0, i);
+          }
+        }
+        int bits = 0;  // Bitwise or of all char codes in list.
+        var list = [];
+        if (end == null) {
+          while (it.moveNext()) {
+            int code = it.current;
+            bits |= code;
+            list.add(code);
+          }
+        } else {
+          for (int i = start; i < end; i++) {
+            if (!it.moveNext()) {
+              throw new RangeError.range(end, start, i);
+            }
+            int code = it.current;
+            bits |= code;
+            list.add(code);
+          }
+        }
+        charCodes = list;
+        isOneByteString = (bits >= 0 && bits <= 0xff);
+        start = 0;
+        end = list.length;
       }
     }
-    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 <= start) return "";
+    if (end == null) {
+      end = codeCount;
+    } else if (end < start || end > codeCount) {
+      throw new RangeError.range(end, start, codeCount);
+    }
     final len = end - start;
     if (!isOneByteString) {
       for (int i = start; i < end; i++) {
         int e = charCodes[i];
         if (e is! _Smi) throw new ArgumentError(e);
         // Is e Latin1?
         if ((e < 0) || (e > 0xFF)) {
           return _createFromCodePoints(charCodes, start, end);
         }
       }
@@ skipping 175 matching lines @@
     }
     return _substringUncheckedNative(startIndex, endIndex);
   }
 
   String _substringUncheckedNative(int startIndex, int endIndex)
       native "StringBase_substringUnchecked";
 
   // Checks for one-byte whitespaces only.
   static bool _isOneByteWhitespace(int codeUnit) {
     if (codeUnit <= 32) {
-      return ((codeUnit == 32) || // Space.
+      return ((codeUnit == 32) ||  // Space.
               ((codeUnit <= 13) && (codeUnit >= 9)));  // CR, LF, TAB, etc.
     }
-    return (codeUnit == 0x85) || (codeUnit == 0xA0);
+    return (codeUnit == 0x85) || (codeUnit == 0xA0);  // NEL, NBSP.
   }
 
   // Characters with Whitespace property (Unicode 6.2).
   // 0009..000D    ; White_Space # Cc       <control-0009>..<control-000D>
   // 0020          ; White_Space # Zs       SPACE
   // 0085          ; White_Space # Cc       <control-0085>
   // 00A0          ; White_Space # Zs       NO-BREAK SPACE
   // 1680          ; White_Space # Zs       OGHAM SPACE MARK
   // 180E          ; White_Space # Zs       MONGOLIAN VOWEL SEPARATOR
   // 2000..200A    ; White_Space # Zs       EN QUAD..HAIR SPACE
@@ skipping 745 matching lines @@
 class _CodeUnits extends Object with ListMixin<int>,
                                      UnmodifiableListMixin<int> {
   /** The string that this is the code units of. */
   String _string;
 
   _CodeUnits(this._string);
 
   int get length => _string.length;
   int operator[](int i) => _string.codeUnitAt(i);
 }