From 621333ea988a823cb6e3a324ed4c459a50771cae Mon Sep 17 00:00:00 2001
From: Conduitry <git@chor.date>
Date: Mon, 13 Jan 2020 21:41:16 -0500
Subject: [PATCH] only add markers to head elements in SSR with hydratable=true
 (#4258)

---
 src/compiler/compile/render_ssr/handlers/Element.ts | 2 +-
 src/compiler/compile/render_ssr/handlers/Title.ts   | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/compiler/compile/render_ssr/handlers/Element.ts b/src/compiler/compile/render_ssr/handlers/Element.ts
index 4c1eca8a9d..e0982a0415 100644
--- a/src/compiler/compile/render_ssr/handlers/Element.ts
+++ b/src/compiler/compile/render_ssr/handlers/Element.ts
@@ -124,7 +124,7 @@ export default function(node: Element, renderer: Renderer, options: RenderOption
 		}
 	});
 
-	if (options.head_id) {
+	if (options.hydratable && options.head_id) {
 		renderer.add_string(` data-svelte="${options.head_id}"`);
 	}
 
diff --git a/src/compiler/compile/render_ssr/handlers/Title.ts b/src/compiler/compile/render_ssr/handlers/Title.ts
index e93ae13d66..a3f271ab1b 100644
--- a/src/compiler/compile/render_ssr/handlers/Title.ts
+++ b/src/compiler/compile/render_ssr/handlers/Title.ts
@@ -5,7 +5,11 @@ import { x } from 'code-red';
 export default function(node: Title, renderer: Renderer, options: RenderOptions) {
 	renderer.push();
 
-	renderer.add_string(`<title data-svelte="${options.head_id}">`);
+	renderer.add_string('<title');
+	if (options.hydratable && options.head_id) {
+		renderer.add_string(` data-svelte="${options.head_id}"`);
+	}
+	renderer.add_string('>');
 
 	renderer.render(node.children, options);