get context at start of {#if} update block instead of at the end (#5531)

Author: jesseskinner

src/compiler/compile/render_dom/wrappers/AwaitBlock.ts

@@ -96,7 +96,7 @@ class AwaitBlockBranch extends Wrapper {
 		`);
 		this.block.chunks.declarations.push(b`${get_context}(#ctx)`);
 		if (this.block.has_update_method) {
-			this.block.chunks.update.push(b`${get_context}(#ctx)`);
+			this.block.chunks.update.unshift(b`${get_context}(#ctx)`);
 		}
 	}
 }

test/runtime/samples/await-then-destruct-object-if/_config.js

@@ -0,0 +1,29 @@
+export default {
+	props: {
+		thePromise: Promise.resolve({ result: 1 })
+	},
+
+	html: '',
+
+	async test({ assert, component, target }) {
+		await (component.thePromise = Promise.resolve({ result: 1 }));
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<p>result: 1</p>
+				<p>count: 0</p>
+			`
+		);
+
+		await new Promise(resolve => setTimeout(resolve, 1));
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<p>result: 1</p>
+				<p>count: 1</p>
+			`
+		);
+	}
+};

test/runtime/samples/await-then-destruct-object-if/main.svelte

@@ -0,0 +1,19 @@
+<script>
+	export let thePromise;
+
+	let count = 0;
+
+	setTimeout(() => {
+		count++;
+	}, 0);
+</script>
+
+{#await thePromise then { result }}
+	{#if result}
+		<p>result: {result}</p>
+		<p>count: {count}</p>
+	{:else}
+		<p>result: {result}</p>
+		<p>count: {count}</p>
+	{/if}
+{/await}