Remove renderElement from Renderer constructor

Remove the argument from all `Renderer` subclass constructor call sites.
In its place, define the default value for the `Renderer.renderElement`
property based on the `static renderElement(currentElement, newElement)`
defined by the inheriting class.

For the sake of consistency, define `MorphRenderer.renderElement` to
no-op. Currently, the `MorphRenderer` class never invokes the
`renderElement` method, so a no-op won't have adverse effects.

src/core/drive/morph_renderer.js

@@ -3,6 +3,9 @@ import { dispatch, nextAnimationFrame } from "../../util"
 import { Renderer } from "../renderer"
 
 export class MorphRenderer extends Renderer {
+  static renderElement(currentElement, newElement) {
+  }
+
   async render() {
     if (this.willRender) await this.#morphBody()
   }

src/core/drive/page_view.js

@@ -19,7 +19,7 @@ export class PageView extends View {
     const shouldMorphPage = this.isPageRefresh(visit) && this.snapshot.shouldMorphPage
     const rendererClass = shouldMorphPage ? MorphRenderer : PageRenderer
 
-    const renderer = new rendererClass(this.snapshot, snapshot, PageRenderer.renderElement, isPreview, willRender)
+    const renderer = new rendererClass(this.snapshot, snapshot, isPreview, willRender)
 
     if (!renderer.shouldRender) {
       this.forceReloaded = true
@@ -32,7 +32,7 @@ export class PageView extends View {
 
   renderError(snapshot, visit) {
     visit?.changeHistory()
-    const renderer = new ErrorRenderer(this.snapshot, snapshot, ErrorRenderer.renderElement, false)
+    const renderer = new ErrorRenderer(this.snapshot, snapshot, false)
     return this.render(renderer)
   }
 

src/core/frames/frame_controller.js

@@ -307,7 +307,7 @@ export class FrameController {
 
     if (newFrameElement) {
       const snapshot = new Snapshot(newFrameElement)
-      const renderer = new FrameRenderer(this, this.view.snapshot, snapshot, FrameRenderer.renderElement, false, false)
+      const renderer = new FrameRenderer(this, this.view.snapshot, snapshot, false, false)
       if (this.view.renderPromise) await this.view.renderPromise
       this.changeHistory()
 

src/core/renderer.js

@@ -3,12 +3,16 @@ import { Bardo } from "./bardo"
 export class Renderer {
   #activeElement = null
 
-  constructor(currentSnapshot, newSnapshot, renderElement, isPreview, willRender = true) {
+  static renderElement(currentElement, newElement) {
+    // Abstract method
+  }
+
+  constructor(currentSnapshot, newSnapshot, isPreview, willRender = true) {
     this.currentSnapshot = currentSnapshot
     this.newSnapshot = newSnapshot
     this.isPreview = isPreview
     this.willRender = willRender
-    this.renderElement = renderElement
+    this.renderElement = this.constructor.renderElement
     this.promise = new Promise((resolve, reject) => (this.resolvingFunctions = { resolve, reject }))
   }