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/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index e2762cd..5758854 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1636,9 +1636,9 @@
   assert(FormatTok->isOneOf(tok::kw_for, tok::kw_while, TT_ForEachMacro) &&
          "'for', 'while' or foreach macro expected");
   nextToken();
-  // JS' for async ( ...
+  // JS' for await ( ...
   if (Style.Language == FormatStyle::LK_JavaScript &&
-      FormatTok->is(Keywords.kw_async))
+      FormatTok->is(Keywords.kw_await))
     nextToken();
   if (FormatTok->Tok.is(tok::l_paren))
     parseParens();