Don't enclose 'this' in braces inside string templates

compiler/frontend/src/org/jetbrains/kotlin/psi/KtExpressionImpl.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.psi
@@ -45,7 +34,7 @@ abstract class KtExpressionImpl(node: ASTNode) : KtElementImpl(node), KtExpressi
                         }
                     }
                     is KtSimpleNameStringTemplateEntry -> {
-                        if (newElement !is KtSimpleNameExpression) {
+                        if (newElement !is KtSimpleNameExpression && !newElement.isThisWithoutLabel()) {
                             val newEntry = parent.replace(KtPsiFactory(expression).createBlockStringTemplateEntry(newElement)) as KtBlockStringTemplateEntry
                             return newEntry.expression!!
                         }
@@ -57,3 +46,5 @@ abstract class KtExpressionImpl(node: ASTNode) : KtElementImpl(node), KtExpressi
         }
     }
 }
+
+private fun PsiElement.isThisWithoutLabel() = this is KtThisExpression && getLabelName() == null