clang-format: [JS] Support for EC6 arrow functions.

Before:
  var b = a.map((x) = > x + 1);

After:
  var b = a.map((x) => x + 1);

llvm-svn: 209112
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index 7a853b0..c10dc96 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -77,6 +77,8 @@
                "            bbbbbb :\n"
                "            ccc;",
                getGoogleJSStyleWithColumns(20));
+
+  verifyFormat("var b = a.map((x) => x + 1);");
 }
 
 TEST_F(FormatTestJS, SpacesInContainerLiterals) {