clang-format: [JS] for await, and fix a crash with for loops.

Summary:
The syntax is actually `for await (const x of y)` (d'oh).
This also fixes a crash for `for` tokens not followed by additional tokens.

Reviewers: djasper

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D33329

llvm-svn: 303382
diff --git a/clang/unittests/Format/FormatTestJS.cpp b/clang/unittests/Format/FormatTestJS.cpp
index ff28f30..c36b435 100644
--- a/clang/unittests/Format/FormatTestJS.cpp
+++ b/clang/unittests/Format/FormatTestJS.cpp
@@ -548,15 +548,14 @@
                "  // Comment.\n"
                "  return async.then();\n"
                "}\n");
-  verifyFormat("for async (const x of y) {\n"
+  verifyFormat("for await (const x of y) {\n"
                "  console.log(x);\n"
                "}\n");
   verifyFormat("function asyncLoop() {\n"
-               "  for async (const x of y) {\n"
+               "  for await (const x of y) {\n"
                "    console.log(x);\n"
                "  }\n"
                "}\n");
-
 }
 
 TEST_F(FormatTestJS, FunctionParametersTrailingComma) {