From 1451a880825a4f0043442b15b45263b953771a9d Mon Sep 17 00:00:00 2001
From: hontas <lundin.pontus@gmail.com>
Date: Thu, 11 Feb 2021 22:42:50 +0100
Subject: [PATCH] simpler isCustomElement & skip extra function call - pass
 options.customElement down to mount_component - remove expensive
 isCustomElement check - only call add_render_callback if not customElement

---
 src/compiler/compile/render_dom/index.ts      |  2 +-
 src/runtime/internal/Component.ts             | 35 +++++++++----------
 .../css-shadow-dom-keyframes/expected.js      |  3 +-
 3 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/src/compiler/compile/render_dom/index.ts b/src/compiler/compile/render_dom/index.ts
index 8e7deb7a78..a56f3fb2b3 100644
--- a/src/compiler/compile/render_dom/index.ts
+++ b/src/compiler/compile/render_dom/index.ts
@@ -485,7 +485,7 @@ export default function dom(
 
 					${css.code && b`this.shadowRoot.innerHTML = \`<style>${css.code.replace(/\\/g, '\\\\')}${options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
 
-					@init(this, { target: this.shadowRoot, props: ${init_props} }, ${definition}, ${has_create_fragment ? 'create_fragment' : 'null'}, ${not_equal}, ${prop_indexes}, ${dirty});
+					@init(this, { target: this.shadowRoot, props: ${init_props}, customElement: true }, ${definition}, ${has_create_fragment ? 'create_fragment' : 'null'}, ${not_equal}, ${prop_indexes}, ${dirty});
 
 					${dev_props_check}
 
diff --git a/src/runtime/internal/Component.ts b/src/runtime/internal/Component.ts
index 3ec939b7b9..5a2a966d0b 100644
--- a/src/runtime/internal/Component.ts
+++ b/src/runtime/internal/Component.ts
@@ -53,27 +53,26 @@ export function claim_component(block, parent_nodes) {
 	block && block.l(parent_nodes);
 }
 
-export function mount_component(component, target, anchor) {
+export function mount_component(component, target, anchor, customElement) {
 	const { fragment, on_mount, on_destroy, after_update } = component.$$;
-	const isCustomElement = Object.getPrototypeOf(component.constructor) === SvelteElement;
 
 	fragment && fragment.m(target, anchor);
 
-	// onMount happens before the initial afterUpdate
-	add_render_callback(() => {
-		// custom element on_mount is called in connectedCallback
-		if (isCustomElement) return;
-
-		const new_on_destroy = on_mount.map(run).filter(is_function);
-		if (on_destroy) {
-			on_destroy.push(...new_on_destroy);
-		} else {
-			// Edge case - component was destroyed immediately,
-			// most likely as a result of a binding initialising
-			run_all(new_on_destroy);
-		}
-		component.$$.on_mount = [];
-	});
+	if (!customElement) {
+		// onMount happens before the initial afterUpdate
+		add_render_callback(() => {
+
+			const new_on_destroy = on_mount.map(run).filter(is_function);
+			if (on_destroy) {
+				on_destroy.push(...new_on_destroy);
+			} else {
+				// Edge case - component was destroyed immediately,
+				// most likely as a result of a binding initialising
+				run_all(new_on_destroy);
+			}
+			component.$$.on_mount = [];
+		});
+	}
 
 	after_update.forEach(add_render_callback);
 }
@@ -161,7 +160,7 @@ export function init(component, options, instance, create_fragment, not_equal, p
 		}
 
 		if (options.intro) transition_in(component.$$.fragment);
-		mount_component(component, options.target, options.anchor);
+		mount_component(component, options.target, options.anchor, options.customElement);
 		flush();
 	}
 
diff --git a/test/js/samples/css-shadow-dom-keyframes/expected.js b/test/js/samples/css-shadow-dom-keyframes/expected.js
index 82a39e5924..4d188201eb 100644
--- a/test/js/samples/css-shadow-dom-keyframes/expected.js
+++ b/test/js/samples/css-shadow-dom-keyframes/expected.js
@@ -40,7 +40,8 @@ class Component extends SvelteElement {
 			this,
 			{
 				target: this.shadowRoot,
-				props: attribute_to_object(this.attributes)
+				props: attribute_to_object(this.attributes),
+				customElement: true
 			},
 			null,
 			create_fragment,