Refactor DrawingRecorders to check for cached drawings earlier

Source/core/paint/BlockFlowPainter.cpp

Index: Source/core/paint/BlockFlowPainter.cpp
diff --git a/Source/core/paint/BlockFlowPainter.cpp b/Source/core/paint/BlockFlowPainter.cpp
index e7cc6442b07763df355665be6c824d19b3a12f02..b031906c3ce9a644c9a55c0cb41fcad9a8b0d469 100644
--- a/Source/core/paint/BlockFlowPainter.cpp
+++ b/Source/core/paint/BlockFlowPainter.cpp
@@ -53,6 +53,9 @@ void BlockFlowPainter::paintSelection(const PaintInfo& paintInfo, const LayoutPo
     if (!m_layoutBlockFlow.shouldPaintSelectionGaps())
         return;
 
+    if (LayoutObjectDrawingRecorder::useCachedDrawingIfPossible(*paintInfo.context, m_layoutBlockFlow, DisplayItem::SelectionGap))
+        return;
+
     LayoutUnit lastTop = 0;
     LayoutUnit lastLeft = m_layoutBlockFlow.logicalLeftSelectionOffset(&m_layoutBlockFlow, lastTop);
     LayoutUnit lastRight = m_layoutBlockFlow.logicalRightSelectionOffset(&m_layoutBlockFlow, lastTop);
@@ -65,9 +68,7 @@ void BlockFlowPainter::paintSelection(const PaintInfo& paintInfo, const LayoutPo
     LayoutObjectDrawingRecorder recorder(*paintInfo.context, m_layoutBlockFlow, DisplayItem::SelectionGap, bounds);
     ClipScope clipScope(paintInfo.context);
 
-    LayoutRect gapRectsBounds = m_layoutBlockFlow.selectionGaps(&m_layoutBlockFlow, paintOffset, LayoutSize(), lastTop, lastLeft, lastRight,
-        recorder.canUseCachedDrawing() ? nullptr : &paintInfo,
-        recorder.canUseCachedDrawing() ? nullptr : &clipScope);
+    LayoutRect gapRectsBounds = m_layoutBlockFlow.selectionGaps(&m_layoutBlockFlow, paintOffset, LayoutSize(), lastTop, lastLeft, lastRight, &paintInfo, &clipScope);
     // TODO(wkorman): Rework below to process paint invalidation rects during layout rather than paint.

[Xianzhu, 2015/07/03 01:24:41]

If this TODO is still valid, then we can't early return here. Otherwise we
should remove the TODO. I guess it's still valid.

[pdr., 2015/07/03 02:38:04]

Good catch. Fixing this required a small amount of logic. We now use
Optional<DrawingRecorder> to skip the creation of the recorder when the cache is
used, but still create it when the cache is not used. There are some simple
optimizations we can make here but I opted to keep this as simple as possible
because wkorman will be removing selection rects soon.

     if (!gapRectsBounds.isEmpty()) {
         DeprecatedPaintLayer* layer = m_layoutBlockFlow.enclosingLayer();