clang-format: [JS] add space before operator 'in'.

Before:
  return ('aaa')in bbbb;

After:
  return ('aaa') in bbbb;

llvm-svn: 218119
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index bf76338..52f45c7 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -81,6 +81,7 @@
                getGoogleJSStyleWithColumns(20));
 
   verifyFormat("var b = a.map((x) => x + 1);");
+  verifyFormat("return ('aaa') in bbbb;");
 }
 
 TEST_F(FormatTestJS, UnderstandsAmpAmp) {