clang-format: [JS] handle let (ES6)

Patch by Martin Probst. Thank you!

llvm-svn: 248713
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index d068d35..c02d51b 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -101,7 +101,9 @@
 
 TEST_F(FormatTestJS, ES6DestructuringAssignment) {
   verifyFormat("var [a, b, c] = [1, 2, 3];");
+  verifyFormat("let [a, b, c] = [1, 2, 3];");
   verifyFormat("var {a, b} = {a: 1, b: 2};");
+  verifyFormat("let {a, b} = {a: 1, b: 2};");
 }
 
 TEST_F(FormatTestJS, ContainerLiterals) {