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

runtime/vm/simulator_arm.cc

Index: runtime/vm/simulator_arm.cc
diff --git a/runtime/vm/simulator_arm.cc b/runtime/vm/simulator_arm.cc
index f3e651482be89bac0a80e3250bf9bdb553f2c678..e06300639ec9267851eadadf76b879c6cb025e3a 100644
--- a/runtime/vm/simulator_arm.cc
+++ b/runtime/vm/simulator_arm.cc
@@ -1171,6 +1171,14 @@ 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);
+}
+
+
 // Returns the top of the stack area to enable checking for stack pointer
 // validity.
 uword Simulator::StackTop() const {