clang-format: Fix bug in wrapping behavior of operators.

Before (even violating the column limit):
  auto Diag =
      diag()
      << aaaaaaaaaaaaaaaa(aaaaaaaaaaaa, aaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaa);

After:
  auto Diag = diag() << aaaaaaaaaaaaaaaa(aaaaaaaaaaaa, aaaaaaaaaaaaa,
                                         aaaaaaaaaaaaaaaaaaaaaaaaaa);

llvm-svn: 297931
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index bcbdbbf..674c3b5 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -4132,6 +4132,9 @@
   verifyFormat(
       "llvm::errs() << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(\n"
       "    aaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaa);");
+  verifyFormat(
+      "auto Diag = diag() << aaaaaaaaaaaaaaaa(aaaaaaaaaaaa, aaaaaaaaaaaaa,\n"
+      "                                       aaaaaaaaaaaaaaaaaaaaaaaaaa);");
 
   verifyFormat("llvm::outs() << \"aaaaaaaaaaaaaaaa: \"\n"
                "             << aaaaaaaa.aaaaaaaaaaaa(aaa)->aaaaaaaaaaaaaa();");