Revert "Remove now unnecessary FormatRewriterContext."

This reverts commit r286262. I accidentally committed it without all of
the changes.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@286264 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Index/CommentToXML.cpp

@@ -535,6 +535,7 @@ public:
                            SimpleFormatContext &SFC,
                            unsigned FUID) :
       FC(FC), Result(Str), Traits(Traits), SM(SM),
+      FormatRewriterContext(SFC),
       FormatInMemoryUniqueId(FUID) { }
 
   // Inline content.
@@ -573,6 +574,7 @@ private:
 
   const CommandTraits &Traits;
   const SourceManager &SM;
+  SimpleFormatContext &FormatRewriterContext;
   unsigned FormatInMemoryUniqueId;
 };