StackValue.Property also needs to implement dupReceiver()

idea/src/org/jetbrains/jet/codegen/StackValue.java

@@ -427,5 +427,17 @@ public abstract class StackValue {
                 v.visitMethodInsn(isStatic ? Opcodes.INVOKESTATIC : isInterface ? Opcodes.INVOKEINTERFACE : Opcodes.INVOKEVIRTUAL, owner, setter.getName(), setter.getDescriptor());
             }
         }
+
+        @Override
+        public void dupReceiver(InstructionAdapter v, int below) {
+            if (!isStatic) {
+                if (below == 1) {
+                    v.dupX1();
+                }
+                else {
+                    v.dup();
+                }
+            }
+        }
     }
 }

idea/testData/codegen/incrementProperty.jet

+class Slot() {
+  var vitality: Int = 10000
+
+  fun increaseVitality(delta: Int) {
+    vitality += delta
+    if (vitality > 65535) vitality = 65535;
+  }
+}
+
+fun box(): String {
+  val s = Slot()
+  s.increaseVitality(1000)
+  return if (s.vitality == 11000) "OK" else "fail"
+}

idea/tests/org/jetbrains/jet/codegen/NamespaceGenTest.java

@@ -414,4 +414,8 @@ public class NamespaceGenTest extends CodegenTestCase {
         final Method main = generateFunction();
         main.invoke(null);  // must not fail
     }
+
+    public void testIncrementProperty() throws Exception {
+        blackBoxFile("incrementProperty.jet");
+    }
 }