Use FormulaTokenArray::FirstToken() in one place where we can

Change-Id: I1ecc1fc69e8be1ba329f2436903654740dbfea9a

sc/source/core/data/clipcontext.cxx

@@ -194,7 +194,7 @@ void CopyFromClipContext::setSingleCell( const ScAddress& rSrcPos, const ScColum
                 ScTokenArray* pCode = rSrcCell.mpFormula->GetCode();
                 if (pCode && pCode->GetLen() == 1)
                 {
-                    const formula::FormulaToken* p = pCode->First();
+                    const formula::FormulaToken* p = pCode->FirstToken();
                     if (p->GetOpCode() == ocTrue || p->GetOpCode() == ocFalse)
                         // This is a boolean formula. Good.
                         break;