Grammar Suggestions are Displayed on the Non-editable Areas

**Describe the bug**
As the text says, grammar suggestions are shown on some non-editable areas (like buttons), and this situation makes the usage less comfortable.

P.S. Sorry for the typo :D

**To Reproduce**
Steps to reproduce the behavior:
1. Go to [Notion](https://www.notion.so)
**Note: You need to _login_ in order to test the consequent steps.**
2. Open a new blank page
3. See error on the buttons grouped under _Get Started With_

**Expected behavior**
I expect to **not to see the suggestions on those areas.**

**Screenshots**

**Platform**
I use Mozilla Firefox, extension version is 0.56.0.

**Additional context**
I have encountered the same problem before at somewhere; if I could remember where did I, I could also report it for a generalized solution.

No source file or test is named. Reproduce the issue in Firefox 0.56.0 on a logged-in Notion page, checking the buttons under “Get Started With,” then trace where suggestions are displayed for non-editable areas. Done means those buttons no longer show grammar suggestions without disrupting editable text checking.

Written by the indexing model from the issue text.