[sksg] More inval fiddling

Node subclasses can now control whether their bounds (changes)
contribute to damage.

Tristate:

  * Default:   The node bounds contribute to damage if the node itself was
               invalidated, observing hasSelfInval().  This is the default
               behavior.

  * ForceSelf: The node bounds contribute to damage, regardless of
               hasSelfInval().  Used for domain-boundary nodes (e.g. Draw),
               which gate blocked fragments (e.g. geometry, paint nodes).

  * BlockSelf: The node bounds do not contribute to damage, regardless of
               hasSelfInval().  Used for nodes which do not contribute
               damage directly (e.g. paints, geometry).

TBR=
Change-Id: I7c941c7ea12e14b008d846ec13108e66e34dbc73
Reviewed-on: https://skia-review.googlesource.com/91104
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>
diff --git a/experimental/sksg/geometry/SkSGPath.cpp b/experimental/sksg/geometry/SkSGPath.cpp
index a04dcf6..ce1ff39 100644
--- a/experimental/sksg/geometry/SkSGPath.cpp
+++ b/experimental/sksg/geometry/SkSGPath.cpp
@@ -18,10 +18,11 @@
     canvas->drawPath(fPath, paint);
 }
 
-SkRect Path::onRevalidate(InvalidationController*, const SkMatrix&) {
+Node::RevalidationResult Path::onRevalidate(InvalidationController*, const SkMatrix&) {
     SkASSERT(this->hasSelfInval());
 
-    return fPath.computeTightBounds();
+    // Geometry does not contribute damage directly.
+    return { fPath.computeTightBounds(), Damage::kBlockSelf };
 }
 
 SkPath Path::onAsPath() const {