Translate WhenUtils to Kotlin

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUnparsingUtils.java

@@ -16,7 +16,6 @@
 
 package org.jetbrains.jet.lang.psi;
 
-import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 

compiler/frontend/src/org/jetbrains/jet/lang/psi/psiUtil/jetPsiUtil.kt

@@ -70,3 +70,6 @@ fun JetClassOrObject.effectiveDeclarations(): List<JetDeclaration> =
         }
 
 fun JetClass.isAbstract() = isTrait() || hasModifier(JetTokens.ABSTRACT_KEYWORD)
+
+[suppress("UNCHECKED_CAST")]
+fun <T: PsiElement> PsiElement.replaced(newElement: T): T = replace(newElement)!! as T