[extensions] Extend workaround for extension hotkeys.

This extends the workaround from https://crrev.com/c/1876809 to also
prevent extensions from forwarding hotkeys to DevTools if they would
normally insert a letter like for example 'h' into a contenteditable
HTML element.

Bug: chromium:923338
Change-Id: I223e4770e5573b2136a2b888b1958308a933986e
Fixed: chromium:1178327
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/4079094
Commit-Queue: Yang Guo <[email protected]>
Auto-Submit: Benedikt Meurer <[email protected]>
Reviewed-by: Yang Guo <[email protected]>
diff --git a/front_end/models/extensions/ExtensionAPI.ts b/front_end/models/extensions/ExtensionAPI.ts
index 108caac..04d576a 100644
--- a/front_end/models/extensions/ExtensionAPI.ts
+++ b/front_end/models/extensions/ExtensionAPI.ts
@@ -1272,7 +1272,8 @@
     // This is a workaround for crbug.com/923338.
     const focused = document.activeElement;
     if (focused) {
-      const isInput = focused.nodeName === 'INPUT' || focused.nodeName === 'TEXTAREA';
+      const isInput =
+          focused.nodeName === 'INPUT' || focused.nodeName === 'TEXTAREA' || (focused as HTMLElement).isContentEditable;
       if (isInput && !(event.ctrlKey || event.altKey || event.metaKey)) {
         return;
       }