unique name for select_block_type in IfBlock#buildCompoundWithOutros

Fixes #1580

src/compile/nodes/IfBlock.ts

@@ -250,7 +250,7 @@ export default class IfBlock extends Node {
 		dynamic,
 		{ name, anchor, hasElse }
 	) {
-		const select_block_type = block.getUniqueName(`select_block_type`);
+		const select_block_type = this.compiler.getUniqueName(`select_block_type`);
 		const current_block_type_index = block.getUniqueName(`current_block_type_index`);
 		const previous_block_index = block.getUniqueName(`previous_block_index`);
 		const if_block_creators = block.getUniqueName(`if_block_creators`);

test/runtime/samples/if-block-outro-unique-select-block-type/Component.html

@@ -0,0 +1 @@
+<div></div>

test/runtime/samples/if-block-outro-unique-select-block-type/_config.js

@@ -0,0 +1,7 @@
+export default {
+	nestedTransitions: true,
+	html: `
+		<div></div>
+		<div></div>
+	`,
+};

test/runtime/samples/if-block-outro-unique-select-block-type/main.html

@@ -0,0 +1,20 @@
+{#if foo}
+	<Component/>
+{:else}
+	<Component/>
+{/if}
+
+{#if foo}
+	<div></div>
+{:else}
+	<div></div>
+{/if}
+
+<script>
+	export default {
+		components: {
+			Component: './Component.html',
+		},
+		data: () => ({ foo: true }),
+	}
+</script>