Disable drawing recorder cache for carets

Source/core/paint/BlockPainter.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/paint/BlockPainter.h"
 
 #include "core/editing/Caret.h"
 #include "core/editing/FrameSelection.h"
 #include "core/frame/LocalFrame.h"
@@ skipping 207 matching lines @@
         if (!m_renderBlock.style()->outlineStyleIsAuto() || !m_renderBlock.isAnonymousBlockContinuation())
             ObjectPainter(m_renderBlock).paintOutline(paintInfo, LayoutRect(paintOffset, m_renderBlock.size()));
     }
 
     if (paintPhase == PaintPhaseOutline || paintPhase == PaintPhaseChildOutlines)
         paintContinuationOutlines(paintInfo, paintOffset);
 
     // If the caret's node's render object's containing block is this block, and the paint action is PaintPhaseForeground,
     // then paint the caret.
     if (paintPhase == PaintPhaseForeground) {
-        RenderDrawingRecorder recorder(paintInfo.context, &m_renderBlock, paintPhase, bounds);
+        RenderDrawingRecorder recorder(paintInfo.context, &m_renderBlock, paintPhase, bounds, DrawingRecorder::DisableCache);

[chrishtr, 2014/12/12 00:18:01]

Add a comment explaining the situation. Also, how exactly do carets paint
without invalidation?

How much work is it for carets to start invalidating their containing block?

[Xianzhu, 2014/12/12 00:24:16]

Actually we already invalidated carets within their containing block. We just
miss the invalidation when caretBrowsing setting changes which is a common bug
of all paint modes. I'm looking into the bug.

This shows that our cached display item assertions are good to discover
under-invalidation bugs :)

         paintCarets(paintInfo, paintOffset);
     }
 }
 
 static inline bool caretBrowsingEnabled(const Frame* frame)
 {
     Settings* settings = frame->settings();
     return settings && settings->caretBrowsingEnabled();
 }
 
@@ skipping 246 matching lines @@
         RenderBlock* block = flow->containingBlock();
         for ( ; block && block != &m_renderBlock; block = block->containingBlock())
             accumulatedPaintOffset.moveBy(block->location());
         ASSERT(block);
         InlinePainter(*flow).paintOutline(info, accumulatedPaintOffset);
     }
 }
 
 
 } // namespace blink