clang-format: [JS] Support exporting abstract classes.

Before:
  export abstract class X {y: number;}
(and all sorts of other havoc in more complicated cases).

After:
  export abstract class X { y: number; }

llvm-svn: 257451
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 5e9a1b5..992331c 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -878,6 +878,7 @@
                "  y: string;\n"
                "}");
   verifyFormat("export class X { y: number; }");
+  verifyFormat("export abstract class X { y: number; }");
   verifyFormat("export default class X { y: number }");
   verifyFormat("export default function() {\n  return 1;\n}");
   verifyFormat("export var x = 12;");