Fix a typo 'iff' => 'if'

llvm-svn: 164766
diff --git a/clang/lib/Frontend/TextDiagnostic.cpp b/clang/lib/Frontend/TextDiagnostic.cpp
index a8a5613..d872e42 100644
--- a/clang/lib/Frontend/TextDiagnostic.cpp
+++ b/clang/lib/Frontend/TextDiagnostic.cpp
@@ -88,7 +88,7 @@
 /// \param SourceLine The line of source
 /// \param i Pointer to byte index,
 /// \param TabStop used to expand tabs
-/// \return pair(printable text, 'true' iff original text was printable)
+/// \return pair(printable text, 'true' if original text was printable)
 ///
 static std::pair<SmallString<16>, bool>
 printableTextForNextCharacter(StringRef SourceLine, size_t *i,