Fix for running with --throw_on_javascript_int_overflow: recognize pattern (a << b) & mask and test…

runtime/lib/integers.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.
 
 // TODO(srdjan): fix limitations.
 // - shift amount must be a Smi.
 class _IntegerImplementation {
   factory _IntegerImplementation._uninstantiable() {
     throw new UnsupportedError(
         "_IntegerImplementation can only be allocated by the VM");
@@ skipping 154 matching lines @@
 
   int pow(int exponent) {
     // Exponentiation by squaring.
     int base = this;
     int result = 1;
     while (exponent != 0) {
       if ((exponent & 1) == 1) {
         result *= base;
       }
       exponent >>= 1;
-      base *= base;
+      // Skip unnecessary operation (can overflow to Mint or Bigint).
+      if (exponent != 0) {
+        base *= base;
+      }
     }
     return result;
   }
 
   String toStringAsFixed(int fractionDigits) {
     return this.toDouble().toStringAsFixed(fractionDigits);
   }
   String toStringAsExponential([int fractionDigits]) {
     return this.toDouble().toStringAsExponential(fractionDigits);
   }
@@ skipping 20 matching lines @@
     if (temp.isEmpty) {
       return "0";
     }
     StringBuffer buffer = new StringBuffer();
     if (isNegative) buffer.write("-");
     for (int i = temp.length - 1; i >= 0; i--) {
       buffer.write(table[temp[i]]);
     }
     return buffer.toString();
   }
+
+  _leftShiftWithMask32(count, mask)  native "Integer_leftShiftWithMask32";
 }
 
 class _Smi extends _IntegerImplementation implements int {
   factory _Smi._uninstantiable() {
     throw new UnsupportedError(
         "_Smi can only be allocated by the VM");
   }
   int get hashCode {
     return this;
   }
@@ skipping 69 matching lines @@
     } else {
       return 0;
     }
   }
   int _shlFromInt(int other) native "Bigint_shlFromInt";
 
   int pow(int exponent) {
     throw "Bigint.pow not implemented";
   }
 }