Issue 4989 - [emscripten] Move filter class files into a separate directory

compiled/filter/Filter.cpp

 #include "Filter.h"
 #include "CommentFilter.h"
 #include "InvalidFilter.h"
 #include "RegExpFilter.h"
 #include "BlockingFilter.h"
 #include "WhitelistFilter.h"
 #include "ElemHideBase.h"
 #include "ElemHideFilter.h"
 #include "ElemHideException.h"
 #include "ElemHideEmulationFilter.h"
-#include "StringMap.h"
+#include "../StringMap.h"
 
 namespace
 {
   StringMap<Filter*> knownFilters(8192);
 
   void NormalizeWhitespace(DependentString& text)
   {
     String::size_type start = 0;
     String::size_type end = text.length();
 
@@ skipping 113 matching lines @@
 
   // This is a hack: we looked up the entry using text but create it using
   // filter->mText. This works because both are equal at this point. However,
   // text refers to a temporary buffer which will go away.
   enter_context("Adding to known filters");
   knownFilter.assign(filter->mText, filter.get());
   exit_context();
 
   return filter.release();
 }