Fix check for uninitialized condition

Fixes sveltejs#4840

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

@@ -392,7 +392,7 @@ export default class IfBlockWrapper extends Wrapper {
 						${snippet && (
 							dependencies.length > 0
 								? b`if (${block.renderer.dirty(dependencies)}) ${condition} = !!${snippet}`
-								: b`if (${condition} == -1) ${condition} = !!${snippet}`
+								: b`if (${condition} == null) ${condition} = !!${snippet}`
 						)}
 						if (${condition}) return ${i};`
 						: b`return ${i};`)}

test/runtime/samples/if-block-static-with-elseif-else-and-outros/RRR.svelte

@@ -0,0 +1 @@
+rrr

test/runtime/samples/if-block-static-with-elseif-else-and-outros/_config.js

@@ -0,0 +1,3 @@
+export default {
+	html: 'eee'
+};

test/runtime/samples/if-block-static-with-elseif-else-and-outros/main.svelte

@@ -0,0 +1,13 @@
+<script>
+	import RRR from './RRR.svelte';
+
+	export let x;
+</script>
+
+{#if "Eva".startsWith('E')}
+	eee
+{:else if x}
+  def
+{:else}
+	<RRR/>
+{/if}