Fix translation of labels with non-identifier names in JS BE

See KT-18027

js/js.parser/src/com/google/gwt/dev/js/JsAstMapper.java

@@ -665,7 +665,7 @@ public class JsAstMapper {
     private JsLabel mapLabel(Node labelNode) throws JsParserException {
         String fromName = labelNode.getFirstChild().getString();
 
-        JsName toName = scopeContext.enterLabel(fromName);
+        JsName toName = scopeContext.enterLabel(fromName, fromName);
 
         Node fromStmt = labelNode.getFirstChild().getNext();
         JsLabel toLabel = new JsLabel(toName);

js/js.parser/src/com/google/gwt/dev/js/ScopeContext.kt

@@ -49,8 +49,8 @@ class ScopeContext(scope: JsScope) {
         exitScope()
     }
 
-    fun enterLabel(ident: String): JsName =
-            (currentScope as JsDeclarationScope).enterLabel(ident)
+    fun enterLabel(ident: String, outputName: String): JsName =
+            (currentScope as JsDeclarationScope).enterLabel(ident, outputName)
 
     fun exitLabel() =
             (currentScope as JsDeclarationScope).exitLabel()