Remove dead declaration from paint_invalidator.h

BTW avoid a possible warning of an uninitialized field (which didn't
actually happen).

Change-Id: I8a895b8a95d394f4652e662402f108331d71a1d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2390968
Auto-Submit: Xianzhu Wang <wangxianzhu@chromium.org>
Commit-Queue: Stephen Chenney <schenney@chromium.org>
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#804243}

third_party/blink/renderer/core/paint/paint_invalidator.h

@@ -99,7 +99,7 @@ struct CORE_EXPORT PaintInvalidatorContext {
   // The previous PaintOffset of FragmentData.
   PhysicalOffset old_paint_offset;
 
-  const FragmentData* fragment_data;
+  const FragmentData* fragment_data = nullptr;
 
  private:
   friend class PaintInvalidator;
@@ -129,9 +129,6 @@ class PaintInvalidator {
   friend struct PaintInvalidatorContext;
   friend class PrePaintTreeWalk;
 
-  ALWAYS_INLINE IntRect ComputeVisualRect(const LayoutObject&,
-                                          const NGPrePaintInfo*,
-                                          const PaintInvalidatorContext&);
   ALWAYS_INLINE void UpdatePaintingLayer(const LayoutObject&,
                                          PaintInvalidatorContext&,
                                          bool is_ng_painting);