Prevent smartSelectExpression from breaking up 'this@outerClass'

The previous commit made JetThisExpression not implement
JetStatementExpression. This had the side effect that
smartSelectExpression over a label-qualified this expression
(e.g 'this@outerClass') would now also list a plain 'this'
as a potential expression. Restore the old behaviour by adding an
explicit check for JetThisExpression.

idea/src/org/jetbrains/jet/plugin/refactoring/JetRefactoringUtil.java

@@ -411,7 +411,7 @@ public class JetRefactoringUtil {
                         addExpression = false;
                     }
                 }
-                else if (element.getParent() instanceof JetCallElement) {
+                else if (element.getParent() instanceof JetCallElement || element.getParent() instanceof JetThisExpression) {
                     addExpression = false;
                 }
                 else if (element.getParent() instanceof JetOperationExpression) {

idea/testData/smartSelection/labelledThis.kt

@@ -0,0 +1,9 @@
+class Foo() {
+    val s = th<caret>is@Foo.toString()
+}
+
+// 'this' should not be listed, only 'this@Foo'
+/*
+this@Foo
+this@Foo.toString()
+*/

idea/tests/org/jetbrains/jet/plugin/SmartSelectionTestGenerated.java

@@ -36,6 +36,11 @@ public class SmartSelectionTestGenerated extends AbstractSmartSelectionTest {
         JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.TestsPackage", new File("idea/testData/smartSelection"), Pattern.compile("^([^\\.]+)\\.kt$"), true);
     }
     
+    @TestMetadata("labelledThis.kt")
+    public void testLabelledThis() throws Exception {
+        doTestSmartSelection("idea/testData/smartSelection/labelledThis.kt");
+    }
+    
     @TestMetadata("simple.kt")
     public void testSimple() throws Exception {
         doTestSmartSelection("idea/testData/smartSelection/simple.kt");