clang-format: [JS] Support more regex literals.

Previously a regex-literal containing "/*" would through clang-format
off, e.g.:
  var regex = /\/*$/;

Would lead to none of the following code to be formatted.

llvm-svn: 220860
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index bc9bbad..6ee150c 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -408,6 +408,10 @@
   verifyFormat("var regex = /\a\\//g;");
   verifyFormat("var regex = /a\\//;\n"
                "var x = 0;");
+  EXPECT_EQ("var regex = /\\/*/;\n"
+            "var x = 0;",
+            format("var regex = /\\/*/;\n"
+                   "var x=0;"));
 }
 
 TEST_F(FormatTestJS, RegexLiteralModifiers) {