[Impeller] disable entity culling by default. (flutter#48717)

From local testing across both flutter galleries, wonderous, some other test apps, the only time this code successfully culls is during the stretch overscroll (and we cull 1 or so entries). The cost of this culling is approximately 20% of entity rendering time, and about 5% of overall raster time.

![image](https://github.com/flutter/engine/assets/8975114/ef85629c-48a8-457f-8385-0c8136404571)

Author: Jonah Williams

impeller/entity/contents/clip_contents.cc

@@ -66,7 +66,7 @@ Contents::StencilCoverage ClipContents::GetStencilCoverage(
 
 bool ClipContents::ShouldRender(
     const Entity& entity,
-    const std::optional<Rect>& stencil_coverage) const {
+    const std::optional<Rect> stencil_coverage) const {
   return true;
 }
 
@@ -163,7 +163,7 @@ Contents::StencilCoverage ClipRestoreContents::GetStencilCoverage(
 
 bool ClipRestoreContents::ShouldRender(
     const Entity& entity,
-    const std::optional<Rect>& stencil_coverage) const {
+    const std::optional<Rect> stencil_coverage) const {
   return true;
 }
 

impeller/entity/contents/clip_contents.h

@@ -35,7 +35,7 @@ class ClipContents final : public Contents {
 
   // |Contents|
   bool ShouldRender(const Entity& entity,
-                    const std::optional<Rect>& stencil_coverage) const override;
+                    const std::optional<Rect> stencil_coverage) const override;
 
   // |Contents|
   bool Render(const ContentContext& renderer,
@@ -76,7 +76,7 @@ class ClipRestoreContents final : public Contents {
 
   // |Contents|
   bool ShouldRender(const Entity& entity,
-                    const std::optional<Rect>& stencil_coverage) const override;
+                    const std::optional<Rect> stencil_coverage) const override;
 
   // |Contents|
   bool Render(const ContentContext& renderer,

impeller/entity/contents/contents.cc

@@ -133,11 +133,10 @@ bool Contents::ApplyColorFilter(
 }
 
 bool Contents::ShouldRender(const Entity& entity,
-                            const std::optional<Rect>& stencil_coverage) const {
+                            const std::optional<Rect> stencil_coverage) const {
   if (!stencil_coverage.has_value()) {
     return false;
   }
-
   auto coverage = GetCoverage(entity);
   if (!coverage.has_value()) {
     return false;

impeller/entity/contents/contents.h

@@ -113,7 +113,7 @@ class Contents {
       const std::string& label = "Snapshot") const;
 
   virtual bool ShouldRender(const Entity& entity,
-                            const std::optional<Rect>& stencil_coverage) const;
+                            const std::optional<Rect> stencil_coverage) const;
 
   //----------------------------------------------------------------------------
   /// @brief  Return the color source's intrinsic size, if available.

impeller/entity/entity.cc

@@ -71,7 +71,11 @@ Contents::StencilCoverage Entity::GetStencilCoverage(
 }
 
 bool Entity::ShouldRender(const std::optional<Rect>& stencil_coverage) const {
+#ifdef IMPELLER_CONTENT_CULLING
   return contents_->ShouldRender(*this, stencil_coverage);
+#else
+  return true;
+#endif  // IMPELLER_CONTENT_CULLING
 }
 
 void Entity::SetContents(std::shared_ptr<Contents> contents) {

impeller/entity/entity_unittests.cc

@@ -1607,6 +1607,20 @@ TEST_P(EntityTest, SolidFillShouldRenderIsCorrect) {
   }
 }
 
+TEST_P(EntityTest, DoesNotCullEntitiesByDefault) {
+  auto fill = std::make_shared<SolidColorContents>();
+  fill->SetColor(Color::CornflowerBlue());
+  fill->SetGeometry(
+      Geometry::MakeRect(Rect::MakeLTRB(-1000, -1000, -900, -900)));
+
+  Entity entity;
+  entity.SetContents(fill);
+
+  // Even though the entity is offscreen, this should still render because we do
+  // not compute the coverage intersection by default.
+  EXPECT_TRUE(entity.ShouldRender(Rect::MakeLTRB(0, 0, 100, 100)));
+}
+
 TEST_P(EntityTest, ClipContentsShouldRenderIsCorrect) {
   // For clip ops, `ShouldRender` should always return true.