Bug 1377329 - Enlarge the default capacity of nsDisplayBuilfer::mFramesMarkedForDisplayList. r=mattwoodrow

For gmail, 100 is too small, enlarge the dafault capaicty of
nsDisplayListBuilder::MarkFramesForDisplayList to prevent reallocation.

MozReview-Commit-ID: 5zSxyakZ5O9

--HG--
extra : rebase_source : a20032ef98fc0e78ddbd4ac8194ee4f11c2e11a7
extra : source : 105804994e32827ff87ea7fcacecf942df41a051

layout/painting/nsDisplayList.cpp

@@ -1279,7 +1279,6 @@ void
 nsDisplayListBuilder::MarkFramesForDisplayList(nsIFrame* aDirtyFrame,
                                                const nsFrameList& aFrames,
                                                const nsRect& aDirtyRect) {
-  mFramesMarkedForDisplay.SetCapacity(mFramesMarkedForDisplay.Length() + aFrames.GetLength());
   for (nsIFrame* e : aFrames) {
     // Skip the AccessibleCaret frame when building no caret.
     if (!IsBuildingCaret()) {
@@ -1291,6 +1290,7 @@ nsDisplayListBuilder::MarkFramesForDisplayList(nsIFrame* aDirtyFrame,
         }
       }
     }
+
     mFramesMarkedForDisplay.AppendElement(e);
     MarkOutOfFlowFrameForDisplay(aDirtyFrame, e, aDirtyRect);
   }

layout/painting/nsDisplayList.h

@@ -1480,7 +1480,7 @@ private:
 
   nsCOMPtr<nsISelection>         mBoundingSelection;
   AutoTArray<PresShellState,8> mPresShellStates;
-  AutoTArray<nsIFrame*,100>    mFramesMarkedForDisplay;
+  AutoTArray<nsIFrame*,400>    mFramesMarkedForDisplay;
   AutoTArray<ThemeGeometry,2>  mThemeGeometries;
   nsDisplayTableItem*            mCurrentTableItem;
   DisplayListClipState           mClipState;