Fix Win64 build of Dart VM.

runtime/vm/locations.h

Index: runtime/vm/locations.h
diff --git a/runtime/vm/locations.h b/runtime/vm/locations.h
index 7a617a3f3d25abd3f1eb542fa7e2f3f6b090a861..91ed897d2632a5ee0aff5bd047e2d12f37fc05a5 100644
--- a/runtime/vm/locations.h
+++ b/runtime/vm/locations.h
@@ -472,17 +472,20 @@ class RegisterSet : public ValueObject {
   }
 
   bool ContainsRegister(Register reg) const {
-    return (cpu_registers_ & (1 << reg)) != 0;
+    return Contains(cpu_registers_, reg);
   }
 
   bool ContainsFpuRegister(FpuRegister fpu_reg) const {
-    return (fpu_registers_ & (1 << fpu_reg)) != 0;
+    return Contains(fpu_registers_, fpu_reg);
   }
 
   intptr_t CpuRegisterCount() const { return RegisterCount(cpu_registers_); }
   intptr_t FpuRegisterCount() const { return RegisterCount(fpu_registers_); }
 
   static intptr_t RegisterCount(intptr_t registers);
+  static bool Contains(intptr_t register_set, intptr_t reg) {
+    return (register_set & (1 << reg)) != 0;
+  }
 
   intptr_t cpu_registers() const { return cpu_registers_; }
   intptr_t fpu_registers() const { return fpu_registers_; }