Remove CSS regions support, keeping a bare minimum to support "region-based" multicol.

Source/core/css/parser/BisonCSSParser.h

Index: Source/core/css/parser/BisonCSSParser.h
diff --git a/Source/core/css/parser/BisonCSSParser.h b/Source/core/css/parser/BisonCSSParser.h
index 2982ab5eec300315c1754ff07adadb449b9f0e76..1a32e94a35df8a7cc0bca3a130b244fb5df9143d 100644
--- a/Source/core/css/parser/BisonCSSParser.h
+++ b/Source/core/css/parser/BisonCSSParser.h
@@ -278,9 +278,6 @@ public:
     bool parseFontFeatureTag(CSSValueList*);
     bool parseFontFeatureSettings(bool important);
 
-    bool parseFlowThread(CSSPropertyID, bool important);
-    bool parseRegionThread(CSSPropertyID, bool important);
-
     bool parseFontVariantLigatures(bool important);
 
     bool parseGeneratedImage(CSSParserValueList*, RefPtr<CSSValue>&);
@@ -313,7 +310,6 @@ public:
     StyleRuleBase* createStyleRule(Vector<OwnPtr<CSSParserSelector> >* selectors);
     StyleRuleBase* createFontFaceRule();
     StyleRuleBase* createPageRule(PassOwnPtr<CSSParserSelector> pageSelector);
-    StyleRuleBase* createRegionRule(Vector<OwnPtr<CSSParserSelector> >* regionSelector, RuleList* rules);
     StyleRuleBase* createMarginAtRule(CSSSelector::MarginBoxType);
     StyleRuleBase* createSupportsRule(bool conditionIsSupported, RuleList*);
     void markSupportsRuleHeaderStart();
@@ -350,9 +346,6 @@ public:
 
     Vector<OwnPtr<CSSParserSelector> >* reusableSelectorVector() { return &m_reusableSelectorVector; }
 
-    void setReusableRegionSelectorVector(Vector<OwnPtr<CSSParserSelector> >* selectors);
-    Vector<OwnPtr<CSSParserSelector> >* reusableRegionSelectorVector() { return &m_reusableRegionSelectorVector; }
-
     void clearProperties();
 
     PassRefPtr<ImmutableStylePropertySet> createStylePropertySet();
@@ -547,7 +540,6 @@ private:
     OwnPtr<Vector<RefPtr<StyleKeyframe> > > m_floatingKeyframeVector;
 
     Vector<OwnPtr<CSSParserSelector> > m_reusableSelectorVector;
-    Vector<OwnPtr<CSSParserSelector> > m_reusableRegionSelectorVector;
 
     RefPtrWillBePersistent<CSSCalcValue> m_parsedCalculation;