Make RenderObject::style() return a const object

Source/core/dom/Element.cpp

Index: Source/core/dom/Element.cpp
diff --git a/Source/core/dom/Element.cpp b/Source/core/dom/Element.cpp
index 2161156c3a9d133da92e8dd6654880f081a3118f..ce27d1ff284e99c1ba04532fc206598d2feb2b0b 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1338,7 +1338,7 @@ bool Element::rendererIsNeeded(const RenderStyle& style)
     return style.display() != NONE;
 }
 
-RenderObject* Element::createRenderer(RenderStyle* style)
+RenderObject* Element::createRenderer(const RenderStyle* style)
 {
     return RenderObject::createObject(this, style);
 }
@@ -1650,7 +1650,7 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change)
     ASSERT(change >= Inherit || needsStyleRecalc());
     ASSERT(parentRenderStyle());
 
-    RefPtr<RenderStyle> oldStyle = renderStyle();
+    RefPtr<RenderStyle> oldStyle = mutableRenderStyle();

[rune, 2015/01/29 23:16:32]

All use of oldStyle below looks const to me.

[Julien - ping for review, 2015/02/10 07:33:19]

RefPtr modifies |oldStyle| so it's not const at all. We could hold onto the raw
pointer but it's tricky as we call setStyle below that could destroy the pointer
under our feet. That's why I think we should stick with mutableRenderStyle here.

     RefPtr<RenderStyle> newStyle = styleForRenderer();
     StyleRecalcChange localChange = RenderStyle::stylePropagationDiff(oldStyle.get(), newStyle.get());
 
@@ -1695,7 +1695,7 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change)
     return localChange;
 }
 
-void Element::updateCallbackSelectors(RenderStyle* oldStyle, RenderStyle* newStyle)
+void Element::updateCallbackSelectors(const RenderStyle* oldStyle, const RenderStyle* newStyle)
 {
     Vector<String> emptyVector;
     const Vector<String>& oldCallbackSelectors = oldStyle ? oldStyle->callbackSelectors() : emptyVector;
@@ -1846,7 +1846,7 @@ bool Element::childTypeAllowed(NodeType type) const
 
 void Element::checkForEmptyStyleChange()
 {
-    RenderStyle* style = renderStyle();
+    const RenderStyle* style = renderStyle();
 
     if (!style && !styleAffectedByEmpty())
         return;
@@ -2538,7 +2538,7 @@ RenderStyle* Element::computedStyle(PseudoId pseudoElementSpecifier)
     // FIXME: Find and use the renderer from the pseudo element instead of the actual element so that the 'length'
     // properties, which are only known by the renderer because it did the layout, will be correct and so that the
     // values returned for the ":selection" pseudo-element will be correct.
-    RenderStyle* elementStyle = renderStyle();
+    RenderStyle* elementStyle = mutableRenderStyle();
     if (!elementStyle) {
         ElementRareData& rareData = ensureElementRareData();
         if (!rareData.computedStyle())
@@ -2621,7 +2621,7 @@ void Element::updatePseudoElement(PseudoId pseudoId, StyleRecalcChange change)
         // Need to clear the cached style if the PseudoElement wants a recalc so it
         // computes a new style.
         if (element->needsStyleRecalc())
-            renderer()->style()->removeCachedPseudoStyle(pseudoId);
+            renderer()->deprecatedMutableStyle()->removeCachedPseudoStyle(pseudoId);
 
         // PseudoElement styles hang off their parent element's style so if we needed
         // a style recalc we should Force one on the pseudo.