[Transforms] fix8155 : Hoist exported enum in system output (#8177)

* Hoist exported enum in system output

* Update baselines

src/compiler/transformers/module/system.ts

@@ -675,6 +675,12 @@ namespace ts {
             const originalNode = getOriginalNode(node);
             if ((originalNode.kind === SyntaxKind.ModuleDeclaration || originalNode.kind === SyntaxKind.EnumDeclaration) && hasModifier(originalNode, ModifierFlags.Export)) {
                 const name = getDeclarationName(<ModuleDeclaration | EnumDeclaration>originalNode);
+                // We only need to hoistVariableDeclaration for EnumDeclaration
+                // as ModuleDeclaration is already hoisted when the transformer call visitVariableStatement
+                // which then call transformsVariable for each declaration in declarationList
+                if (originalNode.kind === SyntaxKind.EnumDeclaration) {
+                    hoistVariableDeclaration(name);
+                }
                 return [
                     node,
                     createExportStatement(name, name)

tests/baselines/reference/systemModuleDeclarationMerging.js

@@ -14,7 +14,7 @@ System.register([], function (exports_1, context_1) {
     "use strict";
     var __moduleName = context_1 && context_1.id;
     function F() { }
-    var F, C, C, E;
+    var F, C, C, E, E;
     exports_1("F", F);
     return {
         setters: [],