*** DO NOT LAND *** Attempt to understand Regions complexity

Source/core/css/StyleInvalidationAnalysis.cpp

Index: Source/core/css/StyleInvalidationAnalysis.cpp
diff --git a/Source/core/css/StyleInvalidationAnalysis.cpp b/Source/core/css/StyleInvalidationAnalysis.cpp
index 440e17fe346b27d1401f0e3ee1da66beb0b17d28..146c0fa0e354aa2adfa189cc10d9a9bde19018e4 100644
--- a/Source/core/css/StyleInvalidationAnalysis.cpp
+++ b/Source/core/css/StyleInvalidationAnalysis.cpp
@@ -123,7 +123,6 @@ static bool ruleAdditionMightRequireDocumentStyleRecalc(StyleRuleBase* rule)
     case StyleRule::Supports: // If we evaluated the supports-clause we could avoid recalc.
     case StyleRule::Viewport: // If the viewport doesn't match, we could avoid recalcing.
     // FIXME: Unclear if any of the rest need to cause style recalc:
-    case StyleRule::Region:
     case StyleRule::Filter:
         return true;