content/static: make playground share links update with edited text

Fixes golang/go#44719

Change-Id: Iedfa4d677b5512f9e140fc647ef6144517e697c1
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/297874
Trust: Jamal Carvalho <jamal@golang.org>
Run-TryBot: Jamal Carvalho <jamal@golang.org>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

content/static/js/playground.js

@@ -87,7 +87,7 @@ export class PlaygroundExampleController {
     this.setOutputText('Waiting for remote server…');
     fetch('/play/share', {
       method: 'POST',
-      body: (_a = this.inputEl) === null || _a === void 0 ? void 0 : _a.textContent,
+      body: (_a = this.inputEl) === null || _a === void 0 ? void 0 : _a.value,
     })
       .then(res => res.text())
       .then(shareId => {

content/static/js/playground.ts

@@ -178,7 +178,7 @@ export class PlaygroundExampleController {
 
     fetch('/play/share', {
       method: 'POST',
-      body: this.inputEl?.textContent,
+      body: this.inputEl?.value,
     })
       .then(res => res.text())
       .then(shareId => {