[Impeller] store all path point data in single buffer.

impeller/display_list/skia_conversions.cc

@@ -57,6 +57,8 @@ Path ToPath(const SkPath& path, Point shift) {
 
   PathBuilder builder;
   PathData data;
+  // Reserve a path size with some arbitrarily additional padding.
+  builder.Reserve(path.countPoints() + 8, path.countVerbs() + 8);
   auto verb = SkPath::Verb::kDone_Verb;
   do {
     verb = iterator.next(data.points);

impeller/geometry/BUILD.gn

@@ -62,6 +62,7 @@ impeller_component("geometry_unittests") {
   sources = [
     "geometry_unittests.cc",
     "matrix_unittests.cc",
+    "path_unittests.cc",
     "rect_unittests.cc",
     "size_unittests.cc",
   ]