[clang-format][NFC] Use UnwrappedLineParser::eof() for consistency

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -213,7 +213,7 @@ void UnwrappedLineParser::parse() {
     }
 
     // Create line with eof token.
-    assert(FormatTok->is(tok::eof));
+    assert(eof());
     pushToken(FormatTok);
     addUnwrappedLine();