[clang-format] Handle "// clang-format off" for RemoveBracesLLVM

clang/lib/Format/Format.cpp

private:
   // Remove optional braces.
   void removeBraces(SmallVectorImpl<AnnotatedLine *> &Lines,
                     tooling::Replacements &Result) {
     const auto &SourceMgr = Env.getSourceManager();
     for (AnnotatedLine *Line : Lines) {
       removeBraces(Line->Children, Result);
       if (!Line->Affected)
         continue;
-      for (FormatToken *Token = Line->First; Token; Token = Token->Next) {
+      for (FormatToken *Token = Line->First; Token && !Token->Finalized;
+           Token = Token->Next) {
         if (!Token->Optional)
           continue;
         assert(Token->isOneOf(tok::l_brace, tok::r_brace));
         assert(Token->Next || Token == Line->Last);
         const auto Start =
             Token == Line->Last || (Token->Next->is(tok::kw_else) &&
                                     Token->Next->NewlinesBefore > 0)
                 ? Token->WhitespaceRange.getBegin()

clang/unittests/Format/FormatTest.cpp

verifyFormat("if (auto *D = dyn_cast<FunctionDecl>(D)) {\n"
                "  if (shouldProcess(D)) {\n"
                "    handleVarDecl(D);\n"
                "  } else {\n"
                "    markAsIgnored(D);\n"
                "  }\n"
                "}",
                Style);
 
+  verifyFormat("// clang-format off\n"
+               "// comment\n"
+               "while (i > 0) { --i; }\n"
+               "// clang-format on\n"
+               "while (j < 0)\n"
+               "  ++j;",
+               "// clang-format off\n"
+               "// comment\n"
+               "while (i > 0) { --i; }\n"
+               "// clang-format on\n"
+               "while (j < 0) { ++j; }",
+               Style);
+
   verifyFormat("if (a)\n"
                "  b; // comment\n"
                "else if (c)\n"
                "  d; /* comment */\n"
                "else\n"
                "  e;",
                "if (a) {\n"
                "  b; // comment\n"