Proper instructions for elvis operator

We should not mark elvis operator unused, for the rhs may have desired side-effects

compiler/tests/org/jetbrains/jet/cfg/ControlFlowTestGenerated.java

@@ -142,6 +142,11 @@ public class ControlFlowTestGenerated extends AbstractControlFlowTest {
         doTest("compiler/testData/cfg/invoke.kt");
     }
     
+    @TestMetadata("lastElvis.kt")
+    public void testLastElvis() throws Exception {
+        doTest("compiler/testData/cfg/lastElvis.kt");
+    }
+    
     @TestMetadata("LazyBooleans.kt")
     public void testLazyBooleans() throws Exception {
         doTest("compiler/testData/cfg/LazyBooleans.kt");

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -1572,6 +1572,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/controlFlowAnalysis/unreachableCode.kt");
             }
             
+            @TestMetadata("unusedElvis.kt")
+            public void testUnusedElvis() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedElvis.kt");
+            }
+            
         }
         
         @TestMetadata("compiler/testData/diagnostics/tests/controlStructures")