[clang] [clang-format][NFC] Clean up fillRanges() in ClangFormat.cpp (PR #143236)

[Owen Pan via cfe-commits]

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@@ -284,27 +284,23 @@ static bool fillRanges(MemoryBuffer *Code,
     errs() << "error: number of -offset and -length arguments must match.\n";
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owenca wrote:

Actually, we can achieve that by handling `Offsets.size() == 1 && Lengths.empty()` separately.

https://github.com/llvm/llvm-project/pull/143236