Add a separate call to initialize the bounds for a sky <iframe> element.

sky/engine/core/BUILD.gn

Index: sky/engine/core/BUILD.gn
diff --git a/sky/engine/core/BUILD.gn b/sky/engine/core/BUILD.gn
index bde047c1195a7c6860de9605514f2bb13f2d5608..9aa3e3c3f153c65b925574da3bb2f6470b97731a 100644
--- a/sky/engine/core/BUILD.gn
+++ b/sky/engine/core/BUILD.gn
@@ -21,6 +21,7 @@ source_set("libraries") {
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/utility",
     "//mojo/public/cpp/system",
+    "//mojo/services/public/cpp/view_manager",
     "//mojo/services/public/interfaces/navigation",
     "//skia",
     "//sky/engine/wtf",