From eae8d21428acdb3fb842df091ded0eb276bcaaaa Mon Sep 17 00:00:00 2001
From: janekptacijarabaci <janekptacijarabaci@seznam.cz>
Date: Tue, 24 Apr 2018 21:39:13 +0200
Subject: moebius#138: Optimize operations on root of deeply-nested frame tree

https://github.com/MoonchildProductions/moebius/pull/138
---
 layout/base/nsPresContext.cpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

(limited to 'layout/base/nsPresContext.cpp')

diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index d9f7b368c..4a54a8432 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -208,6 +208,7 @@ nsPresContext::nsPresContext(nsIDocument* aDocument, nsPresContextType aType)
     mTextZoom(1.0), mFullZoom(1.0), mOverrideDPPX(0.0),
     mLastFontInflationScreenSize(gfxSize(-1.0, -1.0)),
     mPageSize(-1, -1), mPPScale(1.0f),
+    mViewportScrollbarOverrideNode(nullptr),
     mViewportStyleScrollbar(NS_STYLE_OVERFLOW_AUTO, NS_STYLE_OVERFLOW_AUTO),
     mImageAnimationModePref(imgIContainer::kNormalAnimMode),
     mAllInvalidated(false),
@@ -1423,10 +1424,10 @@ nsPresContext::UpdateViewportScrollbarStylesOverride()
   // Start off with our default styles, and then update them as needed.
   mViewportStyleScrollbar = ScrollbarStyles(NS_STYLE_OVERFLOW_AUTO,
                                             NS_STYLE_OVERFLOW_AUTO);
-  nsIContent* propagatedFrom = nullptr;
+  mViewportScrollbarOverrideNode = nullptr;
   // Don't propagate the scrollbar state in printing or print preview.
   if (!IsPaginated()) {
-    propagatedFrom =
+    mViewportScrollbarOverrideNode =
       GetPropagatedScrollbarStylesForViewport(this, &mViewportStyleScrollbar);
   }
 
@@ -1438,13 +1439,13 @@ nsPresContext::UpdateViewportScrollbarStylesOverride()
     // the styles are from, so that the state of those elements is not
     // affected across fullscreen change.
     if (fullscreenElement != document->GetRootElement() &&
-        fullscreenElement != propagatedFrom) {
+        fullscreenElement != mViewportScrollbarOverrideNode) {
       mViewportStyleScrollbar = ScrollbarStyles(NS_STYLE_OVERFLOW_HIDDEN,
                                                 NS_STYLE_OVERFLOW_HIDDEN);
     }
   }
 
-  return propagatedFrom;
+  return mViewportScrollbarOverrideNode;
 }
 
 bool
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