Unable to exit reader mode when Speedreader is disabled

[Tonev]

Description

Users can't exit reader mode if Speedreader is disabled. After opening an article in reader mode, users can't exit the reader mode by clicking on the icon in the address bar.

Steps to Reproduce

1. Ensure Speedreader is disabled via brave://settings/appearance.
2. Open https://www.reuters.com/technology/cryptocurrencies-selloff-widens-bitcoin-down-nearly-4-ether-6-2021-09-07/.
3. Click on the reader mode icon in the address bar to enter reader mode.
4. Click on the reader mode icon in the address bar to exit reader mode.

Actual result:

The article remains in reader mode.

Expected result:

Clicking on the reader mode icon when an article is in reader mode should exit reader mode.

Reproduces how often:

Easily reproduced.

Brave version (brave://version info)

Brave	1.32.4 Chromium: 94.0.4606.50 (Official Build) nightly (64-bit)
Revision	0c1ac2c4842a4746c27c937c1a0453f98da1a972-refs/branch-heads/4606@{#1049}
OS	Windows 7 Service Pack 1 (Build 7601)

Version/Channel Information:

• Can you reproduce this issue with the current release? Yes
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

@stephendonner #17949 (comment)

[stephendonner]

@Tonev thanks a ton for catching and filing this; not sure how I missed it when verifying, before? 😦

/cc @keur

[Tonev]

Happy to help, @stephendonner 😉

[GeetaSarvadnya]

Reproduced on Windows 10 x64 -1.31.66

Brave | 1.31.66 Chromium: 94.0.4606.61 (Official Build) beta (64-bit)
-- | --
Revision | 418b78f5838ed0b1c69bb4e51ea0252171854915-refs/branch-heads/4606@{#1204}
OS | Windows 10 Version 21H1 (Build 19043.1237)

[stephendonner]

Verified PASSED using

Brave	1.38.70 Chromium: 100.0.4896.46 (Official Build) beta (x86_64)
Revision	5ca33821b2211805855c77d334353d27c616a7ca-refs/branch-heads/4896@{#584}
OS	macOS Version 11.6.5 (Build 20G527)

Followed the original steps to reproduce from #18242 (comment).

example	example	example	example	example

Confirmed I was able to enter and exit Speedreader mode at will, including after initial enable/disable.