Don't force recalc if there are no shadow boundary crossing rules

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 ced2bd06440792fe0a24dbe5deac5b25b4f45e55..7d0bc3c61e9488e6dd618bf9c0270a929ecaa870 100644
--- a/Source/core/dom/Element.cpp
+++ b/Source/core/dom/Element.cpp
@@ -1621,7 +1621,7 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change)
     }
 
     if (styleChangeType() >= SubtreeStyleChange)
-        return Force;
+        return document().ensureStyleResolver().treeBoundaryCrossingRules().isEmpty() ? Inherit : Force;

[esprehn, 2013/12/20 19:11:43]

I'm not sure if this will work with adding <style> elements to ShadowRoots since
sorvell said that a <style> in one ShadowRoot should apply to all ShadowRoots.
Does that work yet? We might need to do setNeedsStyleRecalc on each ShadowRoot
in that case.

It might be nice to add a method in StyleResolver.h like
hasTreeBoundaryCrossingRules() const { return ... } to hide the isEmpty() check
since we might not expose that API. We can do that in the future if you don't
want to mess with it in this patch.

 
     return max(localChange, change);
 }