Put PaintInvalidatorContext on the heap, to reduce stack overflows.

third_party/WebKit/Source/core/paint/PaintInvalidator.h

 // Copyright 2016 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.
 
 #ifndef PaintInvalidator_h
 #define PaintInvalidator_h
 
 #include "core/layout/LayoutObject.h"
 #include "core/paint/PaintPropertyTreeBuilder.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/wtf/Vector.h"
 
 namespace blink {
 
 struct PaintInvalidatorContext {
+  USING_FAST_MALLOC(PaintInvalidatorContext);
+
+ public:
   PaintInvalidatorContext() : parent_context(nullptr) {}
 
   PaintInvalidatorContext(const PaintInvalidatorContext& parent_context)
       : parent_context(&parent_context),
         forced_subtree_invalidation_flags(
             parent_context.forced_subtree_invalidation_flags),
         paint_invalidation_container(
             parent_context.paint_invalidation_container),
         paint_invalidation_container_for_stacked_contents(
             parent_context.paint_invalidation_container_for_stacked_contents),
@@ skipping 122 matching lines @@
       PaintInvalidatorContext&);
   ALWAYS_INLINE void UpdateVisualRect(const LayoutObject&,
                                       PaintInvalidatorContext&);
 
   Vector<const LayoutObject*> pending_delayed_paint_invalidations_;
 };
 
 }  // namespace blink
 
 #endif  // PaintInvalidator_h