Revert of Add PaintOptimizations feature to control subsequence caching and empty phase skipping

content/child/runtime_features.cc

Index: content/child/runtime_features.cc
diff --git a/content/child/runtime_features.cc b/content/child/runtime_features.cc
index 4625e2d3eb5d87346204fe1836fc64b18d1ad8fc..a73ed1291a7b4f7d1087e1a24c5cce83732d7e22 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -254,9 +254,6 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
       "FontCacheScaling",
       base::FeatureList::IsEnabled(features::kFontCacheScaling));
 
-  if (!base::FeatureList::IsEnabled(features::kPaintOptimizations))
-    WebRuntimeFeatures::enableFeatureFromString("PaintOptimizations", false);
-
   if (base::FeatureList::IsEnabled(features::kParseHTMLOnMainThread))
     WebRuntimeFeatures::enableFeatureFromString("ParseHTMLOnMainThread", true);