Bug 1289622 - Delegate CalcStyleDifference to a templated helper. r=heycam

layout/style/nsStyleContext.cpp

@@ -891,11 +891,12 @@ nsStyleContext::ApplyStyleFixups(bool aSkipParentDisplayBasedStyleFixup)
 #undef GET_UNIQUE_STYLE_DATA
 }
 
+template<class StyleContextLike>
 nsChangeHint
-nsStyleContext::CalcStyleDifference(nsStyleContext* aNewContext,
-                                    nsChangeHint aParentHintsNotHandledForDescendants,
-                                    uint32_t* aEqualStructs,
-                                    uint32_t* aSamePointerStructs)
+nsStyleContext::CalcStyleDifferenceInternal(StyleContextLike* aNewContext,
+                                            nsChangeHint aParentHintsNotHandledForDescendants,
+                                            uint32_t* aEqualStructs,
+                                            uint32_t* aSamePointerStructs)
 {
   PROFILER_LABEL("nsStyleContext", "CalcStyleDifference",
     js::ProfileEntry::Category::CSS);
@@ -1213,6 +1214,16 @@ nsStyleContext::CalcStyleDifference(nsStyleContext* aNewContext,
   return hint & ~nsChangeHint_NeutralChange;
 }
 
+nsChangeHint
+nsStyleContext::CalcStyleDifference(nsStyleContext* aNewContext,
+                                    nsChangeHint aParentHintsNotHandledForDescendants,
+                                    uint32_t* aEqualStructs,
+                                    uint32_t* aSamePointerStructs)
+{
+  return CalcStyleDifferenceInternal(aNewContext, aParentHintsNotHandledForDescendants,
+                                     aEqualStructs, aSamePointerStructs);
+}
+
 #ifdef DEBUG
 void nsStyleContext::List(FILE* out, int32_t aIndent, bool aListDescendants)
 {

layout/style/nsStyleContext.h

@@ -398,6 +398,14 @@ public:
                                    uint32_t* aEqualStructs,
                                    uint32_t* aSamePointerStructs);
 
+private:
+  template<class StyleContextLike>
+  nsChangeHint CalcStyleDifferenceInternal(StyleContextLike* aNewContext,
+                                           nsChangeHint aParentHintsNotHandledForDescendants,
+                                           uint32_t* aEqualStructs,
+                                           uint32_t* aSamePointerStructs);
+public:
+
   /**
    * Get a color that depends on link-visitedness using this and
    * this->GetStyleIfVisited().