Fix incorrect FIXME.

The case that we wanted to write a test for cannot happen, as the
UnwrappedLineParser already protects against it. Added an assert to
prevent regressions of that assumption.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171720 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index 54999e1..fc4ce10 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -394,6 +394,7 @@
 
 TEST_F(FormatTest, BreaksOnHashWhenDirectiveIsInvalid) {
   EXPECT_EQ("#\n;", format("#;"));
+  verifyFormat("#\n;\n;\n;");
 }
 
 TEST_F(FormatTest, UnescapedEndOfLineEndsPPDirective) {