Do more error checking for '{}'.

This fixes llvm.org/PR14883, where clang-format would run into an
assertion on:

void f() { return } 42

llvm-svn: 172049
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 389c58c..739bcdd 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -1036,6 +1036,10 @@
 // Error recovery tests.
 //===----------------------------------------------------------------------===//
 
+TEST_F(FormatTest, IncorrectCodeTrailingStuff) {
+  verifyFormat("void f() {  return } 42");
+}
+
 TEST_F(FormatTest, IndentationWithinColumnLimitNotPossible) {
   verifyFormat("int aaaaaaaa =\n"
                "    // Overly long comment\n"