Extend selection: select just KDoc if cursor is just before the KDoc (KT-16476)

#KT-16476 Fixed

idea/tests/org/jetbrains/kotlin/idea/WordSelectionTest.java

@@ -123,6 +123,7 @@ public class WordSelectionTest extends KotlinLightCodeInsightFixtureTestCase {
     public void testDeclarationWithComment2() { doTest(); }
     public void testDeclarationWithComment3() { doTest(); }
     public void testDeclarationWithComment4() { doTest(); }
+    public void testDeclarationWithDocComment() { doTest(); }
 
     public void testLeftBrace() { doTest(); }
     public void testRightBrace() { doTest(); }