feat: improve static content stringiciation

Now a single static vnode can contain stringified content
for multiple consecutive nodes, which greatly improves the
coverage of this optimization.

packages/compiler-dom/src/transforms/stringifyStatic.ts

@@ -35,9 +35,29 @@ export const enum StringifyThresholds {
 
 type StringiableNode = PlainElementNode | TextCallNode
 
-// Turn eligible hoisted static trees into stringied static nodes, e.g.
-//   const _hoisted_1 = createStaticVNode(`<div class="foo">bar</div>`)
-// This is only performed in non-in-browser compilations.
+/**
+ * Turn eligible hoisted static trees into stringied static nodes, e.g.
+ *
+ * ```js
+ * const _hoisted_1 = createStaticVNode(`<div class="foo">bar</div>`)
+ * ```
+ *
+ * A single static vnode can contain stringified content for **multiple**
+ * consecutive nodes (element and plain text), called a "chunk".
+ * `@vue/runtime-dom` will create the content via innerHTML in a hidden
+ * container element and insert all the nodes in place. The call must also
+ * provide the number of nodes contained in the chunk so that during hydration
+ * we can know how many nodes the static vnode should adopt.
+ *
+ * The optimization scans a children list that contains hoisted nodes, and
+ * tries to find the largest chunk of consecutive hoisted nodes before running
+ * into a non-hoisted node or the end of the list. A chunk is then converted
+ * into a single static vnode and replaces the hoisted expression of the first
+ * node in the chunk. Other nodes in the chunk are considered "merged" and
+ * therefore removed from both the hoist list and the children array.
+ *
+ * This optimization is only performed in Node.js.
+ */
 export const stringifyStatic: HoistTransform = (children, context) => {
   let nc = 0 // current node count
   let ec = 0 // current element with binding count