More html text preprocessing into vscode process

This does not need to happen in the webview itself

src/vs/workbench/contrib/webview/browser/pre/index.html

@@ -45,9 +45,6 @@
 				},
 				onMessage: (channel, handler) => {
 					handlers[channel] = handler;
-				},
-				preProcessHtml: (text) => {
-					return text.replace(/(?:["'])vscode-resource:([^\s'"]+)(?:["'])/gi, '/vscode-resource$1');
 				}
 			});
 		}());

src/vs/workbench/contrib/webview/browser/pre/main.js

@@ -99,7 +99,6 @@
 	 *   postMessage: (channel: string, data?: any) => void,
 	 *   onMessage: (channel: string, handler: any) => void,
 	 *   injectHtml?: (document: HTMLDocument) => void,
-	 *   preProcessHtml?: (text: string) => void,
 	 *   focusIframeOnCreate?: boolean
 	 * }} HostCommunications
 	 */
@@ -263,7 +262,7 @@
 			host.onMessage('content', (_event, data) => {
 				const options = data.options;
 
-				const text = host.preProcessHtml ? host.preProcessHtml(data.contents) : data.contents;
+				const text = data.contents;
 				const newDocument = new DOMParser().parseFromString(text, 'text/html');
 
 				newDocument.querySelectorAll('a').forEach(a => {

src/vs/workbench/contrib/webview/browser/webviewElement.ts

@@ -152,19 +152,23 @@ export class IFrameWebview extends Disposable implements Webview {
 
 	public set html(value: string) {
 		this.content = {
-			html: value,
+			html: this.preprocessHtml(value),
 			options: this.content.options,
 			state: this.content.state,
 		};
 		this.doUpdateContent();
 	}
 
+	private preprocessHtml(value: string): string {
+		return value.replace(/(?:["'])vscode-resource:([^\s'"]+)(?:["'])/gi, '/vscode-resource$1');
+	}
+
 	public update(html: string, options: WebviewContentOptions, retainContextWhenHidden: boolean) {
 		if (retainContextWhenHidden && html === this.content.html && areWebviewInputOptionsEqual(options, this.content.options)) {
 			return;
 		}
 		this.content = {
-			html: html,
+			html: this.preprocessHtml(html),
 			options: options,
 			state: this.content.state,
 		};
@@ -209,7 +213,6 @@ export class IFrameWebview extends Disposable implements Webview {
 		this._send('message', data);
 	}
 
-
 	layout(): void {
 		// noop
 	}
@@ -217,6 +220,7 @@ export class IFrameWebview extends Disposable implements Webview {
 	focus(): void {
 		this.element.focus();
 	}
+
 	dispose(): void {
 		if (this.element) {
 			if (this.element.parentElement) {