Add a CompareAndSwapUint32 variant to AtomicOperations so that it is possible to a CAS of a 32 bit …

runtime/vm/simulator_mips.cc

Index: runtime/vm/simulator_mips.cc
diff --git a/runtime/vm/simulator_mips.cc b/runtime/vm/simulator_mips.cc
index 5fabae721cc74250693febdd81f711edaeca8afe..f70e54b7ea4135bc63cd34d703c1eac5eddbaa34 100644
--- a/runtime/vm/simulator_mips.cc
+++ b/runtime/vm/simulator_mips.cc
@@ -1191,6 +1191,14 @@ uword Simulator::CompareExchange(uword* address,
 }
 
 
+uint32_t Simulator::CompareExchangeUint32(uint32_t* address,
+                                          uint32_t compare_value,
+                                          uint32_t new_value) {
+  ASSERT(sizeof(uword) == sizeof(uint32_t));
+  return CompareExchange(address, compare_value, new_value);
+}
+
+
 // Calls into the Dart runtime are based on this interface.
 typedef void (*SimulatorRuntimeCall)(NativeArguments arguments);