Issue 4125 - [emscripten] Convert filter classes to C++

compiled/CSSPropertyFilter.h

 #pragma once
 
 #include <cstddef>
 
 #include "Filter.h"
 #include "ElemHideBase.h"
 
 struct CSSPropertyFilterData
 {
   String::size_type mPrefixEnd;
@@ skipping 20 matching lines @@
 
 struct ElemHideData : ElemHideBaseData, CSSPropertyFilterData
 {
 };
 
 class CSSPropertyFilter: public ElemHideBase
 {
 protected:
   CSSPropertyFilterData mPropertyData;
 public:
-  CSSPropertyFilter(const String& text, const ElemHideData& data);
+  explicit CSSPropertyFilter(const String& text, const ElemHideData& data);
   EMSCRIPTEN_KEEPALIVE OwnedString GetRegExpString() const;
   EMSCRIPTEN_KEEPALIVE const DependentString GetSelectorPrefix() const
   {
     return mPropertyData.GetSelectorPrefix(mText, mData.mSelectorStart);
   }
   EMSCRIPTEN_KEEPALIVE const DependentString GetSelectorSuffix() const
   {
     return mPropertyData.GetSelectorSuffix(mText);
   }
 };