[De-AMP] Regex does not check for empty value of ⚡ attribute

[ShivanKaul]

From: https://bravesoftware.slack.com/archives/C03BE3VNL06/p1651027881491089?thread_ts=1650911256.912569&cid=C03BE3VNL06

"Regarding the buggy behavior: Our amp-detection (in part) looks for the ⚡ attribute without an explicit value (i.e. [⚡] vs [⚡=''] ). When the attribute is followed by ='', it no longer matches our current regular expression.
There is no reason why a web-author would provide the empty value, so this pattern is not likely to be encountered often, if ever, in the wild. That said, we found a scenario today which could yield this pattern.
When setting out to test an NBCNews AMP page locally, I downloaded the page via right-click, Save As on Windows. This process modifies the markup in a couple ways, one of which includes adding ='' after the ⚡ attribute.
So if an individual were to download an AMP page (via Save As), and re-upload it elsewhere, we would not properly bounce/redirect visitors to the second version."

We have this check for amp="", but not ⚡=""

[stephendonner]

Verified PASSED using

Brave	1.40.75 Chromium: 102.0.5005.61 (Official Build) beta (x86_64)
Revision	0e59bcc00cc4985ce39ad31c150065f159d95ad3-refs/branch-heads/5005@{#819}
OS	macOS Version 12.5 (Build 21G5027d)

Followed the testplan/steps from brave/brave-core#13182 (comment)

Steps:

1. installed 1.40.75
2. launched Brave
3. loaded https://shivankaul.com/brave/de-amp/test-amp-lightning-empty-attribute.html and confirmed it redirected to brave.com, with Auto-redirect AMP pages toggled to ON/Enabled in brave://settings/shields
4. new profile
5. toggled Auto-redirect AMP pages to OFF/Disabled via brave://settings/shields
6. loaded https://shivankaul.com/brave/de-amp/test-amp-lightning-empty-attribute.html and confirmed it did NOT redirect

Auto-redirect ON	Auto-redirect OFF

[MadhaviSeelam]

Verification PASSED using

Brave | 1.40.80 Chromium: 102.0.5005.78 (Official Build) beta (64-bit)
-- | --
Revision | df6dbb5a9fd82af3f567198af2eb5fb4876ef99c-refs/branch-heads/5005_59@{#3}
OS | Windows 11 Version 21H2 (Build 22000.675)

Followed the testplan/steps from brave/brave-core#13182 (comment)

Steps:

• Installed 1.40.80
• Launched Brave
• Loaded https://shivankaul.com/brave/de-amp/test-amp-lightning-empty-attribute.html and confirmed it redirected to brave.com, with Auto-redirect AMP pages toggled to ON/Enabled in brave://settings/shields
• New profile
• Toggled Auto-redirect AMP pages to OFF/Disabled via brave://settings/shields
• Loaded https://shivankaul.com/brave/de-amp/test-amp-lightning-empty-attribute.html and confirmed it did NOT redirect

Auto-redirect ON	Auto-redirect OFF

[kjozwiak]

Verification PASSED on Samsung S10+ running Android 12 using the following build(s):

Brave | 1.40.101 Chromium: 103.0.5060.42 (Official Build) (64-bit)
--- | ---
Revision | de0d840bf9439c31bd86bf74f065c31fdf9b208d-refs/branch-heads/5060@{#667}
OS | Android 12; Build/SP1A.210812.016

Went through the STR/Cases outlined via brave/brave-core#13182 (comment) as per the following:

• installed/launched 1.40.101 Chromium: 103.0.5060.42
• loaded https://shivankaul.com/brave/de-amp/test-amp-lightning-empty-attribute.html and ensured that it redirected to brave.com, with Auto-redirect AMP pages toggled to ON/Enabled via Settings -> Brave Shields & privacy
• removed/re-installed to launch 1.40.101 Chromium: 103.0.5060.42 via a new profile
• toggled Auto-redirect AMP pages to OFF/Disabled via Settings -> Brave Shields & privacy
• loaded https://shivankaul.com/brave/de-amp/test-amp-lightning-empty-attribute.html and ensured it did NOT redirect

Auto-redirect ON	Auto-redirect OFF