clang-format: [JS] terminate import sorting on export type X = Y

Contributed by @jankuehle!

https://reviews.llvm.org/D150116 introduced a bug. `export type X = Y` was considered an export declaration and took part in import sorting. This is not correct. With this change `export type X = Y` properly terminates import sorting.

Reviewed By: krasimir

Differential Revision: https://reviews.llvm.org/D150563

clang/lib/Format/SortJavaScriptImports.cpp

@@ -517,7 +517,7 @@ private:
     }
 
     // eat a potential "import X, " prefix.
-    if (Current->is(tok::identifier)) {
+    if (!Reference.IsExport && Current->is(tok::identifier)) {
       Reference.DefaultImport = Current->TokenText;
       nextToken();
       if (Current->is(Keywords.kw_from))

clang/unittests/Format/SortImportsTestJS.cpp

@@ -503,6 +503,15 @@ TEST_F(SortImportsTestJS, ImportExportType) {
   verifySort("export {A, type B} from 'foo';\n",
              "export {A} from 'foo';\n"
              "export   {type B} from 'foo';");
+
+  // `export type X = Y;` should terminate import sorting. The following export
+  // statements should therefore not merge.
+  verifySort("export type A = B;\n"
+             "export {X};\n"
+             "export {Y};\n",
+             "export type A = B;\n"
+             "export {X};\n"
+             "export {Y};\n");
 }
 
 } // end namespace