Render textarea binding values inside element

* ssr-textarea-bind-fix

* oops

* trying again

* Fixing an old test

* avoid creating extra function expression

src/compiler/compile/render-ssr/handlers/Element.ts

@@ -146,6 +146,9 @@ export default function(node: Element, renderer: Renderer, options: RenderOption
 
 		if (name === 'group') {
 			// TODO server-render group bindings
+		} else if (binding.name === 'value' && node.name === 'textarea') {
+			const snippet = snip(expression);
+			textarea_contents='${(' + snippet + ') || ""}';
 		} else {
 			const snippet = snip(expression);
 			opening_tag += ' ${(v => v ? ("' + name + '" + (v === true ? "" : "=" + JSON.stringify(v))) : "")(' + snippet + ')}';

test/runtime/samples/binding-textarea/_config.js

@@ -9,7 +9,7 @@ export default {
 	`,
 
 	ssrHtml: `
-		<textarea value="some text"></textarea>
+		<textarea>some text</textarea>
 		<p>some text</p>
 	`,
 

test/server-side-rendering/samples/text-area-bind/_expected.html

@@ -0,0 +1 @@
+<textarea>hello</textarea>

test/server-side-rendering/samples/text-area-bind/main.svelte

@@ -0,0 +1,5 @@
+<script>
+	  let value = 'hello';
+</script>
+
+<textarea bind:value></textarea>