Bug 1275452 - Part 2: Eagerly restyle native anonymous content in stylo. r=bholley

--HG--
extra : rebase_source : d0e728b4edcd32482743e98f5aecd22c669354f1

layout/base/nsCSSFrameConstructor.cpp

@@ -4241,6 +4241,13 @@ nsCSSFrameConstructor::GetAnonymousContent(nsIContent* aParent,
     }
   }
 
+  if (ServoStyleSet* styleSet = mPresShell->StyleSet()->GetAsServo()) {
+    // Eagerly compute styles for the anonymous content tree.
+    for (auto& info : aContent) {
+      styleSet->RestyleSubtree(info.mContent);
+    }
+  }
+
   return NS_OK;
 }