[css-size-adjust] text-size-adjust is non-negative

[ewilligers]

Like other sizing properties, text-size-adjust does not
accept negative values.

[ewilligers]

Note also that in Firefox and Blink, 'none' computes to '100%'.

Perhaps the spec should change
Computed value: specfied keyword or percentage
to
Computed value: specfied percentage, or 'auto'

[emilio]

Note also that in Firefox and Blink, 'none' computes to '100%'.

How are you determining this? I don't think Firefox supports text-size-adjust: <percentage> to begin with.

[ewilligers]

My mistake. I guess I made the mistake because a test passes in Firefox, but that would be because Firefox doesn't support the property, so test_computed_value succeeds immediately.

[tabatkins]

Lack of support causing a test to pass means the test is written badly - test_computed_value() should fail or throw in that case.

[ewilligers]

Lack of support causing a test to pass means the test is written badly - test_computed_value() should fail or throw in that case.

Test now changed: chromium / WPT

[ewilligers]

@dbaron please review

[ewilligers]

@tantek please review.

This avoids the warning

LINE ~69: The biblio refs [[CSS2]] and [[CSS21]] are both aliases of the same base reference [[CSS2]]. Please choose one name and use it consistently.

and forbids negative values. Note the browsers already reject negative values:
https://wpt.fyi/results/css/css-size-adjust/parsing/text-size-adjust-invalid.html?label=master&label=experimental

[ewilligers]

@litherum please review.
WPTs exist for valid non-negative and invalid negative percentages.