fix bitmask overflow when using slotted components (sveltejs#4077)

Author: Conduitry

src/compiler/compile/render_dom/Renderer.ts

@@ -220,7 +220,11 @@ export default class Renderer {
 				const i = (value / 31) | 0;
 				const n = 1 << (value % 31);
 
-				if (!bitmask[i]) bitmask[i] = { n: 0, names: [] };
+				if (bitmask.length <= i) {
+					for (let j = bitmask.length; j <= i; j++) {
+						bitmask[j] = { n: 0, names: [] };
+					}
+				}
 
 				bitmask[i].n |= n;
 				bitmask[i].names.push(name);

test/runtime/samples/bitmask-overflow-3/_config.js

@@ -0,0 +1,3 @@
+export default {
+	error: `A is not defined`,
+};

test/runtime/samples/bitmask-overflow-3/main.svelte

@@ -0,0 +1,4 @@
+<script>
+	let x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15, x16, x17, x18, x19, x20, x21, x22, x23, x24, x25, x26, x27, x28, x29, x30, x31;
+</script>
+<A>foo</A>